View source for Thai language

{{Short description|Tai language}}
{{Distinguish|Tai languages|Central Tai languages}}
{{Use dmy dates|date=November 2022}}
{{Infobox language
| name             = Thai
| altname          = Central Thai, Siamese
| image            = Thai_Language_(in_Thai).svg
| imagecaption     = "{{Lang|th-latn|Phasa Thai|italic=no}}" (literally meaning "Thai language") written in [[Thai script]]
| nativename       = {{Lang|th|ภาษาไทย|italic=no}}, {{Lang|th-latn|Phasa Thai}}
| pronunciation    = {{IPA|th|pʰāːsǎːtʰāj|}}
| script           = {{indented plainlist|
* [[Thai script]]
* [[Thai Braille]]
* [[Khom Thai script|Khom Thai]] (religious use)
}}
| region           = {{indented plainlist|
* [[Thailand]] ([[Central Thailand]] and Thai Chinese enclaves throughout country)
* [[Cambodia]] ([[Koh Kong District|Koh Kong]])
* [[Myanmar]] ([[Tanintharyi Region|Tanintharyi]])}}
| ethnicity        = [[Thai people|Central Thai]], [[Thai Chinese]], [[Mon people|Mon]], [[Lao Wiang]], [[Phuan people|Phuan]]
| speakers         = [[first language|L1]]: {{sigfig|27.177030|2}} million
| date             = 2024
| ref              = <ref name="Ethnologue28|tha">{{Ethnologue28|tha}}</ref>
| speakers2        = {{ubli|[[second language|L2]]: {{sigfig|44.206500|2}} million (2024)<ref>{{Ethnologue28|nan}}</ref> | Total: {{sigfig|71.383530|2}} million (2024)<ref name="Ethnologue28|tha">{{Ethnologue28|tha}}</ref>}}
| speakers_label   = Speakers
| familycolor      = Kradai
| fam2             = [[Kam–Tai languages|Kam–Tai]]
| fam3             = [[Tai languages|Tai]]
| fam4             = [[Southwestern Tai languages|Southwestern]]
| nation           = Thailand
| minority         = {{ubli|[[Cambodia]]|[[Laos]]|[[Malaysia]]|[[Myanmar]]}}
| agency           = [[Royal Society of Thailand]]
| iso1             = th
| iso2             = tha
| iso3             = tha
| glotto           = thai1261
| glottorefname    = Thai
| lingua           = 47-AAA-b
| notice           = Indic
| notice2          = IPA
| ancestor         = 
| map              = Idioma tailandés.png
| mapcaption       = {{legend|dodgerblue|Majority}}
{{legend|lightblue|Minority}}
| imagealt         = "Phasa Thai" (ภาษาไทย) in Thai script
| fam5             = Chiang Saen
}}
[[File:WIKITONGUES- Dang speaking Thai.webm|thumb|A native Thai speaker, recorded in [[Bangkok]]]]
'''Thai''',<ref group="lower-alpha" name="Explanation 1">In {{langx|th|{{Wikt-lang|th|ภาษาไทย}}|link=no}} {{Transliteration|th|RTGS|[[Royal Thai General System of Transcription|Phasa Thai]]}}</ref> or '''Central Thai'''{{efn|In {{langx|th|{{Wikt-lang|th|ภาษาไทยกลาง}}|link=no}} {{Transliteration|th|RTGS|Phasa Thai Klang}}; not to be confused with ''[[Central Tai]]''}} (historically '''Siamese''';{{efn|In {{langx|th|ภาษาสยาม|link=no}} {{Transliteration|th|RTGS|Phasa Sayam}}}}<ref group=lower-alpha name="Explanation 2">Although "Thai" and "Central Thai" have become more common, the older term, "Siamese", is still used by linguists, especially when it is being distinguished from other [[Tai languages]] (Diller 2008:6{{Full citation needed|date=November 2012}}). "Proto-Thai" is, for example, the ancestor of all of [[Southwestern Tai]], not just Siamese (Rischel 1998{{Full citation needed|date=November 2012}}).</ref> {{langx|th|ภาษาไทย|link=no}}), is a [[Tai language]] of the [[Kra–Dai languages|Kra–Dai]] [[language family]] spoken by the [[Thai people|Central Thai]], [[Mon people|Mon]], [[Lao Wiang]], and [[Phuan people|Phuan]] people in Central Thailand and the vast majority of [[Thai Chinese]] enclaves throughout the country. It is the sole [[official language]] of [[Thailand]].<ref>{{Cite book|last1=Diller|first1=A.|title=National identity and its defenders: Thailand today|last2=Reynolds|first2=Craig J.|date=2002|publisher=Silkworm Books|isbn=974-7551-88-8|editor-last=Reynolds|location=Chiang Mai|chapter=What makes central Thai a national language?|oclc=54373362}}</ref><ref>{{cite book|last=Draper|first=John|chapter=Language education policy in Thailand |title=The Routledge International Handbook of Language Education Policy in Asia|pages=229–242|location=Abingdon, Oxfordshire; New York City |publisher=Routledge |date=2019 |doi=10.4324/9781315666235-16|isbn=978-1-315-66623-5|s2cid=159127015}}</ref>

Thai is the most spoken of over 60 [[languages of Thailand]] by both number of native and overall speakers. Over half of its vocabulary is derived from or borrowed from [[Pali]], [[Sanskrit]], [[Mon language|Mon]]<ref>{{Cite book|title=A history of Thailand|last=Baker|first=Christopher|publisher=Cambridge University Press|year=2014|isbn=978-1-316-00733-4|location=Melbourne, Australia|pages=3–4}}</ref> and [[Old Khmer]]. It is a [[tonal language|tonal]] and [[analytic language]]. Thai has a complex [[orthography]] and system of [[marker (linguistics)|relational markers]]. Spoken Thai, depending on standard [[Sociolinguistics|sociolinguistic]] factors such as age, gender, class, spatial proximity, and the urban/rural divide, is partly [[mutual intelligibility|mutually intelligible]] with [[Lao language|Lao]], [[Isan language|Isan]], and some fellow [[Southwestern Tai languages|Thai topolects]]. These languages are written with slightly different scripts, but are linguistically similar and effectively form a [[dialect continuum]].<ref>{{Cite journal|last=Enfield|first=N. J.|title=How to define 'Lao', 'Thai', and 'Isan' language? A view from linguistic science|journal=Tai Culture|volume=3|issue=1|pages=62–67}}</ref>

The Thai language is spoken by over 70 million people in Thailand as of 2024.<ref name="Ethnologue28|tha">{{Ethnologue28|tha}}</ref> Moreover, most Thais in the northern (Lanna) and the northeastern (Isan) parts of the country today are bilingual speakers of Central Thai and their respective regional dialects because Central Thai is the language of television, education, news reporting, and all forms of media.<ref name=bangkok>{{cite web|url= http://thaiarc.tu.ac.th/thai/peansiri.htm |title= Linguistic Perspectives of Thai Culture |access-date= 26 April 2011 |author= Peansiri Vongvipanond |date= Summer 1994 |work= paper presented to a workshop of teachers of social science |publisher= University of New Orleans |page= 2 |quote= The dialect one hears on radio and television is the Bangkok dialect, considered the standard dialect. |archive-url= https://web.archive.org/web/20121120062746/http://thaiarc.tu.ac.th/thai/peansiri.htm |archive-date= 20 November 2012 |url-status= dead}}</ref> A recent research found that the speakers of the [[Northern Thai language]] (also known as Phasa Mueang or Kham Mueang) have become so few, as most people in northern Thailand now invariably speak Standard Thai, so that they are now using mostly Central Thai words and only seasoning their speech with the "Kham Mueang" accent.<ref>{{cite journal|first1=Pim|last1=Kemasingki|first2= Pariyakorn|last2= Prateepkoh|title= Kham Mueang: the slow death of a language|journal= Chiang Mai City Life|date= August 1, 2017|page=8|quote=there are still many people speaking kham mueang, but as an accent, not as a language. Because we now share the written language with Bangkok, we are beginning to use its vocabulary as well|url=http://www.chiangmaicitylife.com/citylife-articles/rip-kham-mueang-the-slow-death-of-a-language/}}</ref> [[standard language|Standard Thai]] is based on the [[linguistic register|register]] of the educated classes by Central Thai and ethnic minorities in the area along [[Bangkok Metropolitan Region|the ring surrounding the Metropolis]].<ref>{{cite book |title= Language and national identity in Asia |first= Andrew |last=Simpson |year= 2007 |publisher= Oxford University Press |quote= Standard Thai is a form of Central Thai based on the variety of Thai spoken earlier by the elite of the court, and now by the educated middle and upper classes of Bangkok. It ... was standardized in grammar books in the nineteenth century, and spread dramatically from the 1930s onwards, when public education became much more widespread}}</ref><ref>{{Cite journal|last=Thepboriruk|first=Kanjana|date=2010|title=Bangkok Thai tones revisited|url=https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxzZWFsc2pvdXJuYWx8Z3g6NDljZWJlMjUzMGE0NGYyMw|journal=Journal of the Southeast Asian Linguistic Society|publisher=University of Hawaii Press|volume=3|issue=1|pages=86–105|quote=Linguists generally consider Bangkok Thai and Standard Thai, the Kingdom's national language, to be one and the same.}}</ref>

In addition to Central Thai, Thailand is home to other related [[Tai languages]]. Although most linguists classify these dialects as related but distinct languages, native speakers often identify them as regional variants or dialects of the "same" Thai language, or as "different kinds of Thai".<ref>{{Citation |first1=Antonio L. |last1=Rappa |first2=Lionel |last2=Wee |title=Language Policy and Modernity in Southeast Asia: Malaysia, the Philippines, Singapore, and Thailand |publisher=Springer |year=2006 |pages=114–115}}</ref> As a [[Lingua franca|dominant language]] in all aspects of society in Thailand, Thai initially saw gradual and later widespread adoption as a [[second language]] among the country's [[Ethnic groups in Thailand|minority ethnic groups]] from the mid-late [[Ayutthaya Kingdom|Ayutthaya]] period onward.<ref>{{cite book |last1=Lieberman |first1=Victor |title=Strange Parallels |volume=1: Integration on the Mainland: Southeast Asia in Global Context, c. 800–1830 |series=Studies in Comparative World History |date=2003 |pages=|isbn=978-0-521-80086-0|edition=Kindle }}</ref><ref>{{cite book |last=Wyatt |first=David K. |title=Thailand: A Short History |year=2003 |publisher=Yale University Press |place=New Haven, Connecticut |isbn=0-300-08475-7 }}</ref> Ethnic minorities today are predominantly bilingual, speaking Thai alongside their native language or dialect.

== Classification ==
{{Further|Kra–Dai languages|Tai languages|Tai peoples}}
Standard Thai is classified as one of the Chiang Saen languages—others being [[Northern Thai language|Northern Thai]], [[Southern Thai language|Southern Thai]] and numerous smaller languages, which together with the Northwestern Tai and Lao-Phutai languages, form the [[Southwestern Tai languages|Southwestern]] branch of [[Tai languages]]. The Tai languages are a branch of the [[Kra–Dai languages|Kra–Dai language family]], which encompasses a large number of indigenous languages spoken in an arc from [[Hainan]] and [[Guangxi]] south through Laos and Northern Vietnam to the Cambodian border.

Standard Thai is the principal language of education and government and spoken throughout Thailand. The standard is based on the dialect of the central Thai people, and it is written in the [[Thai script]].
[[File:"tooth" in Kra-Dai languages.svg|thumb|384x384px|Example of divergence among the Kra-Dai Languages]]
{{clade
|label1=[[Kra-Dai languages|Kra-Dai]]
|1={{clade
|    1=[[Hlai languages]]
|    2=[[Kam-Sui languages]]
|    3=[[Kra languages]]
|    4=[[Be language]]
|    label5=[[Tai languages]]
|    5={{clade
|       1=[[Northern Tai languages]]
|       2=[[Central Tai languages]]
|  label4=[[Southwestern Tai languages]]
|       4={{clade
|           label1=Northwestern Tai languages
|                1={{clade
|                  1=[[Khamti language]]
|                  2=[[Tai Lue language]]
|                  3=[[Shan language]]
|                  4=others}}
|           label2=Chiang Saen languages
|                2={{clade
|                  1=[[Northern Thai language]]
|                  label2=Sukhothai language
|                       2={{clade
|                       1='''Thai language'''
|                       2=[[Southern Thai language]]}}}}
|           label3=Lao-Phuthai languages
|                3={{clade
|                  1=[[Tai Yo language]]
|                  2=[[Phu Thai language|Phuthai language]]
|                  3=[[Lao language]] (PDR Lao, [[Isan language]])
}}
}}
}}
}}
}}

== History ==
{{More citations needed section|date=May 2020}}
Thai has undergone various historical sound changes. Some of the most significant changes occurred during the evolution from Old Thai to modern Thai.<ref name="Wilaiwan" /> The Thai writing system has an eight-century history and many of these changes, especially in consonants and tones, are evidenced in the modern [[Thai script|orthography]].

===Early spread===
According to a Chinese source, during the [[Ming dynasty]], [[Yingya Shenglan]] (1405–1433), [[Ma Huan]] reported on the language of the [[Ayutthaya kingdom|Xiānluó]] (暹羅) or Ayutthaya Kingdom,{{efn|Xiānluó was the Chinese name for Ayutthaya, a kingdom created by the merger of [[Lavo Kingdom|Lavo]] and [[Sukhothai Kingdom|Sukhothai]] or Suvarnabhumi.}} saying that it somewhat resembled the local patois as pronounced in [[Guangdong]]<ref>{{Citation|title=Ying-yai Sheng-lan: The Overall Survey of the Ocean's Shores (1433)|date=1970|publisher=Hakluyt Society at the University Press|isbn=0-521-01032-2}}</ref>{{rp|107}} [[Phra Nakhon Si Ayutthaya (city)|Ayutthaya]], the old capital of Thailand from 1351 - 1767 A.D., was from the beginning a bilingual society, speaking Thai and [[Khmer language|Khmer]]. Bilingualism must have been strengthened and maintained for some time by the great number of Khmer-speaking captives the Thais took from Angkor Thom after their victories in 1369, 1388 and 1431.<ref>Kasetsiri 1999: 25</ref> Gradually toward the end of the period, a language shift took place. Khmer fell out of use. Both Thai and Khmer descendants whose great-grand parents or earlier ancestors were bilingual came to use only Thai. In the process of language shift, an abundance of Khmer elements were transferred into Thai and permeated all aspects of the language. Consequently, the Thai of the late Ayutthaya Period which later became Ratanakosin or Bangkok Thai, was a thorough mixture of Thai and Khmer. There were more Khmer words in use than Tai cognates. Khmer grammatical rules were used actively to coin new disyllabic and polysyllabic words and phrases. Khmer expressions, sayings, and proverbs were expressed in Thai through transference.

Thais borrowed both the Royal vocabulary and rules to enlarge the vocabulary from Khmer.<ref>Varasarin 1984: 91</ref> The Thais later developed the royal vocabulary according to their immediate environment. Thai and Pali, the latter from Theravada Buddhism, were added to the vocabulary. An investigation of the Ayutthaya Rajasap reveals that three languages, Thai, Khmer and Khmero-Indic were at work closely both in formulaic expressions and in normal discourse. In fact, Khmero-Indic may be classified in the same category as Khmer because Indic had been adapted to the Khmer system first before the Thai borrowed.

===Old Thai===

Old Thai had a three-way tone distinction on "live syllables" (those not ending in a stop), with no possible distinction on "dead syllables" (those ending in a stop, i.e. either {{IPA|/p/, /t/, /k/}} or the [[glottal stop]] that automatically closes syllables otherwise ending in a short vowel).

There was a two-way voiced vs. voiceless distinction among all [[fricative]] and [[sonorant]] consonants, and up to a four-way distinction among [[stop consonant|stops]] and [[affricate]]s. The maximal four-way occurred in [[labial consonant|labials]] ({{IPA|/p pʰ b ʔb/}}) and [[denti-alveolar consonant|denti-alveolars]] ({{IPA|/t tʰ d ʔd/}}); the three-way distinction among [[velar consonant|velars]] ({{IPA|/k kʰ ɡ/}}) and [[palatal consonant|palatals]] ({{IPA|/tɕ tɕʰ dʑ/}}), with the glottalized member of each set apparently missing.

The major change between old and modern Thai was due to voicing distinction losses and the concomitant [[tone split]]. This may have happened between about 1300 and 1600 CE, possibly occurring at different times in different parts of the Thai-speaking area.<ref name="Wilaiwan" /> All voiced–voiceless pairs of consonants lost the voicing distinction:
*Plain voiced stops ({{IPA|/b d ɡ dʑ/}}) became voiceless aspirated stops ({{IPA|/pʰ tʰ kʰ tɕʰ/}}).<ref group=lower-alpha name="Explanation 4">The glottalized stops {{IPA|/ʔb ʔd/}} were unaffected, as they were treated in every respect like voiceless unaspirated stops due to the initial glottal stop. These stops are often described in the modern language as phonemically plain stops {{IPA|/b d/}}, but the glottalization is still commonly heard.</ref>
*Voiced fricatives became voiceless.
*Voiceless sonorants became voiced.
However, in the process of these mergers, the former distinction of voice was transferred into a new set of tonal distinctions. In essence, every tone in Old Thai split into two new tones, with a lower-pitched tone corresponding to a syllable that formerly began with a voiced consonant, and a higher-pitched tone corresponding to a syllable that formerly began with a voiceless consonant (including glottalized stops). An additional complication is that formerly voiceless unaspirated stops/affricates (original {{IPA|/p t k tɕ ʔb ʔd/}}) also caused original tone 1 to lower, but had no such effect on original tones 2 or 3.

The above consonant mergers and tone splits account for the complex relationship between spelling and sound in modern Thai. Modern "low"-class consonants were voiced in Old Thai, and the terminology "low" reflects the lower tone variants that resulted. Modern "mid"-class consonants were voiceless unaspirated stops or affricates in Old Thai—precisely the class that triggered lowering in original tone 1 but not tones 2 or 3. Modern "high"-class consonants were the remaining voiceless consonants in Old Thai (voiceless fricatives, voiceless sonorants, voiceless aspirated stops). The three most common tone "marks" (the lack of any tone mark, as well as the two marks termed ''mai ek'' and ''mai tho'') represent the three tones of Old Thai, and the complex relationship between tone mark and actual tone is due to the various tonal changes since then. Since the tone split, the tones have changed in actual representation to the point that the former relationship between lower and higher tonal variants has been completely obscured. Furthermore, the six tones that resulted after the three tones of Old Thai were split have since merged into five in standard Thai, with the lower variant of former tone 2 merging with the higher variant of former tone 3, becoming the modern "falling" tone.<ref group=lower-alpha name="Explanation 5">Modern [[Lao language|Lao]], [[Isan language|Isan]] and [[Northern Thai language|northern Thai dialects]] are often described as having six tones, but these are not necessarily due to preservation of the original six tones resulting from the tone split. For example, in standard Lao, both the high and low variants of Old Thai tone 2 merged; however, the mid-class variant of tone 1 became pronounced differently from either the high-class or low-class variants, and all three eventually became phonemic due to further changes, e.g. {{IPA|/kr/}} > {{IPA|/kʰ/}}. For similar reasons, Lao has developed more than two tonal distinctions in "dead" syllables.</ref>

==== Old Thai (Sukhothai) consonant inventory ====
{| class="wikitable"
!
! colspan="4" |[[Labial consonant|Labial]]
! colspan="4" |[[Dental consonant|Dental]]/ <br> [[Alveolar consonant|Alveolar]]
! colspan="3" |([[Alveolo-palatal consonant|Alveolo-]]) <br> [[Palatal consonant|Palatal]]
! colspan="3" |[[Velar consonant|Velar]]
! colspan="1" |[[Glottal consonant|Glottal]]
|-
![[Nasal stop|Nasal]]
| colspan="2" |{{IPAblink|m̊}}
{{Lang|th|หม|italic=no}}
| colspan="2" |{{IPAblink|m}}
{{Lang|th|ม|italic=no}}
| colspan="2" |{{IPAblink|n̊}}
{{Lang|th|หน|italic=no}}
| colspan="2" |{{IPAblink|n}}
{{Lang|th|น, ณ|italic=no}}
| colspan="2" |{{IPAblink|ɲ̊}}
{{Lang|th|หญ|italic=no}}
|{{IPAblink|ɲ}}
{{Lang|th|ญ|italic=no}}
| colspan="2" |{{IPAblink|ŋ̊}}
{{Lang|th|หง|italic=no}}
|{{IPAblink|ŋ}}
{{Lang|th|ง|italic=no}}
|
|-
![[Plosive]]/<br />[[Affricate]]
|{{IPAblink|p}}
{{Lang|th|ป|italic=no}}
|{{IPAblink|pʰ}}
{{Lang|th|ผ|italic=no}}
|{{IPAblink|b}}
{{Lang|th|พ, ภ|italic=no}}
|{{IPA|[ʔb]}}
{{Lang|th|บ|italic=no}}
|{{IPAblink|t}}
{{Lang|th|ฏ, ต|italic=no}}
|{{IPAblink|tʰ}}
{{Lang|th|ฐ, ถ|italic=no}}
|{{IPAblink|d}}
{{Lang|th|ท, ธ|italic=no}}
|{{IPA|[ʔd]}}
{{Lang|th|ฎ, ด|italic=no}}
|{{IPAblink|tɕ}}
{{Lang|th|จ|italic=no}}
|{{IPAblink|tɕʰ}}
{{Lang|th|ฉ|italic=no}}
|{{IPAblink|dʑ}}
{{Lang|th|ช|italic=no}}
|{{IPAblink|k}}
{{Lang|th|ก|italic=no}}
|{{IPAblink|kʰ}}
{{Lang|th|ข|italic=no}}
|{{IPAblink|g}}
{{Lang|th|ค, ฆ|italic=no}}
|{{IPAblink|ʔ}}
{{Lang|th|อ|italic=no}}
|-
![[Fricative consonant|Fricative]]
| colspan="2" |{{IPAblink|f}}
{{Lang|th|ฝ|italic=no}}
| colspan="2" |{{IPAblink|v}}
{{Lang|th|ฟ|italic=no}}
| colspan="2" |{{IPAblink|s}}
{{Lang|th|ศ, ษ, ส|italic=no}}
| colspan="5" |{{IPAblink|z}}~{{IPAblink|ʑ}}
{{Lang|th|ซ|italic=no}}
| colspan="2" |{{IPAblink|x}}
{{Lang|th|ฃ|italic=no}}
|{{IPAblink|ɣ}}
{{Lang|th|ฅ|italic=no}}
|{{IPAblink|h}}
{{Lang|th|ห|italic=no}}
|-
![[Trill consonant|Trill]]
| colspan="4" |
| colspan="2" |{{IPAblink|r̊}}
{{Lang|th|หร|italic=no}}
| colspan="2" |{{IPAblink|r}}
{{Lang|th|ร|italic=no}}
| colspan="7" |
|-
![[Approximant consonant|Approximant]]
| colspan="2" |{{IPAblink|ẘ}}
{{Lang|th|หว|italic=no}}
| colspan="2" |{{IPAblink|w}}
'''ว'''
| colspan="2" |{{IPAblink|l̥}}
'''หล'''
| colspan="2" |{{IPAblink|l}}
'''ล'''
|{{IPAblink|j̊}}
'''หย'''
| colspan="4" |
|{{IPAblink|j}}
'''ย'''
|{{IPA|[ʔj]}}
'''อย'''
|}

==== Historical Sukhothai pronunciation ====
{| class="wikitable"
!Letters
!IPA
!Word in Sukhothai (in Modern Thai script)
!Pronunciation in IPA (excluding tone)
!Meaning and Definitions
|-
| colspan="5" |'''<nowiki>วรรค ก | Varga Kor</nowiki>'''
|-
|'''ก'''
|'''k'''
|เกิด
|kɤːt
|''v.'' to be born
|-
|'''ข'''
|'''kʰ'''
|ของ
|kʰɔːŋ
|''n.'' thing
|-
|'''ฃ'''
|'''x'''
|ฃึ้น (ขึ้น)
|xɯn
|''v.'' to go up
|-
|'''ค'''
|'''g'''
|ครู
|gruː
|''n.'' teacher
|-
|'''ฅ'''
|'''ɣ'''
|ฅวาม (ความ)
|ɣwaːm
|''n.'' affair; matter; content
|-
|'''ฆ'''
|'''g'''
|ฆ่า
|gaː
|''v.'' to kill
|-
|'''ง'''
|'''ŋ'''
|งก
|ŋok
|''adj.'' greedy
|-
|'''หง'''
|'''ŋ̊'''
|หงอก
|ŋ̊ɔːk
|''v.'' to whiten (''[[hair]]'')
|-
| colspan="5" |'''<nowiki>วรรค จ | Varga Jor</nowiki>'''
|-
|'''จ'''
|'''tɕ'''
|ใจ
|tɕaɯ
|''n.'' heart
|-
|'''ฉ'''
|'''tɕʰ'''
|ฉาย
|tɕʰaːj
|''v.'' to shine (on something)
|-
|'''ช'''
|'''dʑ'''
|ชื่อ
|dʑɯː
|''n.'' name
|-
|'''ซ'''
|'''z - ʑ'''
|ซ้ำ
|zam
|''adv.'' repeatedly
|-
|'''ญ'''
|'''ɲ'''
|ญวน
|ɲuan
|''n.'' [[Vietnam]] (''archaic'')
|-
|'''หญ'''
|'''ɲ̊'''
|หญิง
|ɲ̊iŋ
|''n.'' woman
|-
| colspan="5" |'''<nowiki>วรรค รฏ | Varga Ra Tor</nowiki>'''
|-
|'''ฎ'''
|'''ʔd'''
|ฎีกา
|ʔdiː.kaː
|''n.'' petition notice
|-
|'''ฏ'''
|'''t'''
|ฏาร
|taː.raʔ
|''n.'' [[Ganymede (moon)|Ganymede]]
|-
|'''ฐ'''
|'''tʰ'''
|ฐาน
|tʰaːn
|''n.'' base, platform
|-
|'''ณ'''
|'''n'''
|เณร
|neːn
|''n.'' novice monk
|-
| colspan="5" |'''<nowiki>วรรค ต | Varga Tor</nowiki>'''
|-
|'''ด'''
|'''ʔd'''
|ดาว
|ʔdaːw
|n. star
|-
|'''ต'''
|'''t'''
|ตา
|taː
|''n.'' [[eye]]
|-
|'''ถ'''
|'''tʰ'''
|ถอย
|tʰɔj
|''v.'' to move back
|-
|'''ท'''
|'''d'''
|ทอง
|dɔːŋ
|''n.'' [[gold]]
|-
|'''ธ'''
|'''d'''
|ธุระ
|du.raʔ
|''n.'' business; affairs; errands
|-
|'''น'''
|'''n'''
|น้ำ
|naːm
|''n.'' [[water]]
|-
|'''หน'''
|'''n̊'''
|หนู
|n̊uː
|''n.'' [[mouse]]
|-
| colspan="5" |'''<nowiki>วรรค ป | Varga Por</nowiki>'''
|-
|'''บ'''
|'''ʔb'''
|บ้าน
|ʔbaːn
|''n.'' house
|-
|'''ป'''
|'''p'''
|ปลา
|plaː
|''n.'' fish
|-
|'''ผ'''
|'''pʰ'''
|ผึ้ง
|pʰɯŋ
|''n.'' [[bee]]
|-
|'''ฝ'''
|'''f'''
|ฝัน
|fan
|''n.'' dream
|-
|'''พ'''
|'''b'''
|พ่อ
|bɔː
|''n.'' father
|-
|'''ฟ'''
|'''v'''
|ฟัน
|van
|''n.'' tooth
|-
|'''ภ'''
|'''b'''
|ภาษา
|baː.saː
|''n.'' [[language]]
|-
|'''ม'''
|'''m'''
|แม่
|mɛː
|''n.'' mother
|-
|'''หม'''
|'''m̊'''
|หมา
|m̊aː
|''n.'' dog
|-
| colspan="5" |'''<nowiki>อวรรค | Avarga</nowiki>'''
|-
|'''อย'''
|'''ʔj'''
|อย่า
|ʔjaː
|''adv.'' do not
|-
|'''ย'''
|'''j'''
|เย็น
|jen
|''adj.'' cold
|-
|'''หย'''
|'''j̊'''
|เหยียบ
|j̊iap
|''v.'' to step on
|-
|'''ร'''
|'''r'''
|รัก
|rak
|''v.'' to love
|-
|'''หร'''
|'''r̊'''
|หรือ
|r̊ɯː
|''conj.'' or
|-
|'''ล'''
|'''l'''
|ลม
|lom
|''n.'' wind
|-
|'''หล'''
|'''l̥'''
|หล่อ
|l̥ɔː
|''adj.'' handsome
|-
|'''ว'''
|'''w'''
|วัน
|wan
|''n.'' day
|-
|'''หว'''
|'''ẘ'''
|หวี
|ẘiː
|''n.'' comb
|-
|'''ศ'''
|'''s'''
|ศาล
|saːn
|''n.'' court of law
|-
|'''ษ'''
|'''s'''
|ฤๅษรี (ฤๅษี)
|rɯː.siː
|''n.'' hermit
|-
|'''ส'''
|'''s'''
|สวย
|suaj
|''adj.'' beautiful
|-
|'''อ'''
|'''ʔ'''
|อ้าย
|ʔaːj
|''n.'' first born son
|}

==== Early Old Thai ====
{{further|Proto-Tai}}
Early Old Thai also apparently had velar fricatives {{IPA|/x ɣ/}} as distinct phonemes. These were represented by the now-obsolete letters ฃ ''kho khuat'' and ฅ ''kho khon'', respectively. During the Old Thai period, these sounds merged into the corresponding stops {{IPA|/kʰ ɡ/}}, and as a result the use of these letters became unstable.

At some point in the history of Thai, an alveolo-palatal nasal phoneme {{IPA|/ɲ/}} also existed, inherited from [[Proto-Tai]]. A letter ญ ''yo ying'' also exists, which is used to represent an alveolo-palatal nasal in words borrowed from [[Sanskrit]] and [[Pali]], and is currently pronounced {{IPA|/j/}} at the beginning of a syllable but {{IPA|/n/}} at the end of a syllable.  Most native Thai words that are reconstructed as beginning with {{IPA|/ɲ/}} are also pronounced {{IPA|/j/}} in modern Thai, but generally spelled with ย ''yo yak'', which consistently represents {{IPA|/j/}}. This suggests that {{IPA|/ɲ/}} > {{IPA|/j/}} in native words occurred in the pre-literary period. It is unclear whether Sanskrit and Pali words beginning with {{IPA|/ɲ/}} were borrowed directly with a {{IPA|/j/}}, or whether a {{IPA|/ɲ/}} was re-introduced, followed by a second change {{IPA|/ɲ/}} > {{IPA|/j/}}. The [[northeastern Thai]] dialect [[Isan language|Isan]] and the [[Lao language]] still preserve the phoneme /ɲ/, which is represented in the [[Lao script]] by  ຍ, such as in the word  ຍຸງ ({{IPA|/ɲúŋ/}}, ''mosquito''). This letter is distinct from the phoneme {{IPA|/j/}} and its Lao letter ຢ, such as in the word  ຢາ ({{IPA|/jàː/}}, ''medicine''). The distinction in writing has been lost in the informal writing of the Isan language with the Thai script and both sounds are represented by ย {{IPA|/j/}} (See: [[Comparison of Lao and Isan]]).

Proto-Tai also had a glottalized palatal sound, reconstructed as {{IPA|/ʔj/}} in Li Fang-Kuei (1977{{Full citation needed|date=November 2012}}). Corresponding Thai words are generally spelled หย, which implies an Old Thai pronunciation of {{IPA|/hj/}} (or {{IPA|/j̊/}}), but a few such words are spelled อย, which implies a pronunciation of {{IPA|/ʔj/}} and suggests that the glottalization may have persisted through to the early literary period.

=== Vowel developments ===
The vowel system of modern Thai contains nine pure vowels and three centering diphthongs, each of which can occur short or long. According to Li (1977{{Full citation needed|date=November 2012}}), however, many Thai dialects have only one such short–long pair ({{IPA|/a aː/}}), and in general it is difficult or impossible to find minimal short–long pairs in Thai that involve vowels other than {{IPA|/a/}} and where both members have frequent correspondences throughout the Tai languages.  More specifically, he notes the following facts about Thai:
*In [[open syllable]]s, only long vowels occur. (This assumes that all apparent cases of short open syllables are better described as ending in a glottal stop.  This makes sense from the lack of tonal distinctions in such syllables, and the glottal stop is also reconstructible across the Tai languages.)
*In [[closed syllable]]s, the long high vowels {{IPA|/iː ɯː uː/}} are rare, and cases that do exist typically have diphthongs in other Tai languages.
*In closed syllables, both short and long mid {{IPA|/e eː o oː/}} and low {{IPA|/ɛ ɛː ɔ ɔː/}} do occur.  However, generally, only words with short {{IPA|/e o/}} and long {{IPA|/ɛː ɔː/}} are reconstructible back to Proto-Tai.
*Both of the mid back unrounded vowels {{IPA|/ɤ ɤː/}} are rare, and words with such sounds generally cannot be reconstructed back to Proto-Tai.
Furthermore, the vowel that corresponds to short Thai {{IPA|/a/}} has a different and often higher quality in many of the Tai languages compared with the vowel corresponding to Thai {{IPA|/aː/}}.

This leads Li to posit the following:
#Proto-Tai had a system of nine pure vowels with no length distinction, and possessing approximately the same qualities as in modern Thai: high {{IPA|/i ɯ u/}}, mid {{IPA|/e ɤ o/}}, low {{IPA|/ɛ a ɔ/}}.
#All Proto-Tai vowels were lengthened in open syllables, and low vowels were also lengthened in closed syllables.
#Modern Thai largely preserved the original lengths and qualities, but lowered {{IPA|/ɤ/}} to {{IPA|/a/}}, which became short {{IPA|/a/}} in closed syllables and created a phonemic length distinction {{IPA|/a aː/}}.  Eventually, length in all other vowels became phonemic as well and a new {{IPA|/ɤ/}} (both short and long) was introduced, through a combination of borrowing and sound change.  Li believes that the development of long {{IPA|/iː ɯː uː/}} from diphthongs, and the lowering of {{IPA|/ɤ/}} to {{IPA|/a/}} to create a length distinction {{IPA|/a aː/}}, had occurred by the time of Proto-Southwestern-Tai, but the other missing modern Thai vowels had not yet developed.

Not all researchers agree with Li. Pittayaporn (2009{{Full citation needed|date=November 2012}}), for example, reconstructs a similar system for Proto-Southwestern-Tai, but believes that there was also a mid back unrounded vowel {{IPA|/ə/}} (which he describes as {{IPA|/ɤ/}}), occurring only before final velar {{IPA|/k ŋ/}}.  He also seems to believe that the Proto-Southwestern-Tai vowel length distinctions can be reconstructed back to similar distinctions in Proto-Tai.

== Phonology ==
{{IPA notice}}

=== Consonants ===

==== Initials ====
Standard Thai distinguishes three [[voice-onset time]]s among plosive and affricate consonants:
*[[voiced consonant|voiced]]
*[[tenuis consonant|tenuis]] (unvoiced, unaspirated)
*[[aspirated consonant|aspirated]]

Where English makes a distinction between voiced {{IPA|/b/}} and unvoiced aspirated {{IPA|/pʰ/}}, Thai distinguishes a third sound – the unvoiced, unaspirated {{IPA|/p/}} that occurs in English only as an allophone of {{IPA|/pʰ/}}, for example after an {{IPA|/s/}} as in the sound of the ''p'' in "spin". There is similarly a laminal denti-alveolar{{Citation needed|date=April 2024}} {{IPA|/d/}}, {{IPA|/t/}}, {{IPA|/tʰ/}} triplet in Thai. In the velar series there is a {{IPA|/k/}}, {{IPA|/kʰ/}} pair and in the postalveolar series a {{IPA|/tɕ/}}, {{IPA|/tɕʰ/}} pair, without the corresponding voiced sounds {{IPA|/ɡ/}} and {{IPA|/dʑ/}}. (In loanwords from English, English {{IPA|/ɡ/}} and {{IPA|/d͡ʒ/}} are borrowed as the tenuis stops {{IPA|/k/}} and {{IPA|/tɕ/}}.)

In each cell below, the first line indicates [[help:IPA|International Phonetic Alphabet]] (IPA), the second indicates the Thai characters in initial position. Note that several letters appearing in the same box have identical pronunciation. In such cases, one of the letters may serve as the "default", being more common and/or preferred for borrowings from English and such; for example, น in the case of "n" and ส for "s". The letter ห, the default "h" letter, is also used to help write certain tones (described below).

{|class="wikitable" style=text-align:center
! colspan=2|
! [[Labial consonant|Labial]]
! [[Dental consonant|Dental]]/ <br> [[Alveolar consonant|Alveolar]]
! ([[Alveolo-palatal consonant|Alveolo-]]) <br> [[Palatal consonant|Palatal]]
! [[Velar consonant|Velar]]
! [[Glottal consonant|Glottal]]
|-
! colspan=2| [[Nasal consonant|Nasal]]
| style="background-color: #ccf" | {{IPAslink|m}}<br />ม
| style="background-color: #cfc" | {{IPAslink|n}}<br />ณ, น
|
| style="background-color: #fcc" | {{IPAslink|ŋ}}<br />ง
|
|-
! rowspan=3| [[Plosive]]/<br />[[Affricate]]
! <small>[[voiced consonant|voiced]]</small>
| style="background-color: #ccf" | {{IPAslink|b}}<br />บ
| style="background-color: #cfc" | {{IPAslink|d̪|d}}<br />ฎ, ด
|
|
|
|-
! <small>[[tenuis consonant|tenuis]]</small>
| style="background-color: #ccf" | {{IPAslink|p}}<br />ป
| style="background-color: #cfc" | {{IPAslink|t̪|t}}<br />ฏ, ต
| style="background-color: #fcf" | {{IPAslink|tɕ}}<br />จ
| style="background-color: #fcc" | {{IPAslink|k}}<br />ก
| style="background-color: #ccc" | {{IPAslink|ʔ}}<br />อ{{efn|Initial อ is silent and therefore considered as a [[glottal stop]].}}
|-
! <small>[[aspirated consonant|aspirated]]</small>
| style="background-color: #ccf" | {{IPAslink|pʰ}}<br />ผ, พ, ภ
| style="background-color: #cfc" | {{IPAslink|tʰ}}<br />ฐ, ฑ, ฒ, ถ, ท, ธ
| style="background-color: #fcf" | {{IPAslink|tɕʰ}}<br />ฉ, ช, ฌ
| style="background-color: #fcc" | {{IPAslink|kʰ}}<br />ข, ฃ, ค, ฅ, ฆ{{efn|ฃ and ฅ are no longer used. Thus, modern Thai is said to have 42 consonant letters.}}
|
|-
! colspan=2| [[Fricative]]
| style="background-color: #ccf" | {{IPAslink|f}}<br />ฝ, ฟ
| style="background-color: #ffc" | {{IPAslink|s}}<br />ซ, ศ, ษ, ส
|
|
| style="background-color: #ccc" | {{IPAslink|h}}<br />ห, ฮ
|-

! colspan=2| [[Approximant]]
| style="background-color: #cff" | {{IPAslink|w}}<br />ว
| style="background-color: #cff" | {{IPAslink|l}}<br />ล, ฬ
| style="background-color: #cff" | {{IPAslink|j}}<br />ญ, ย
|
|
|-
! colspan=2| [[Rhotic consonant|Rhotic]]/[[Liquid consonant|Liquid]]
|
| style="background-color: #cff" | {{IPAslink|r}}<br />ร
|
|
|
|}

==== Finals ====
Although the overall 44 Thai consonant letters provide 21 sounds in case of initials, the case for finals is different. For finals, only eight sounds, as well as no sound, called ''mātrā'' ({{Wikt-lang|th|มาตรา}}) are used. To demonstrate, at the end of a syllable, บ ({{IPA|/b/}}) and ด ({{IPA|/d/}}) are devoiced, becoming pronounced as {{IPA|/p/}} and {{IPA|/t/}} respectively. Additionally, all plosive sounds are [[Unreleased stop|unreleased]]. Hence, final {{IPA|/p/}}, {{IPA|/t/}}, and {{IPA|/k/}} sounds are pronounced as {{IPA|[p̚]}}, {{IPA|[t̚]}}, and {{IPA|[k̚]}} respectively.

Of the consonant letters, excluding the disused ฃ and ฅ, six (ฉ ผ ฝ ห อ ฮ) cannot be used as a final and the other 36 are grouped as following.

{|class="wikitable" style=text-align:center
!
! [[Labial consonant|Labial]]
! [[Alveolar consonant|Alveolar]]
! [[Palatal consonant|Palatal]]
! [[Velar consonant|Velar]]
! [[Glottal consonant|Glottal]]
|-
! [[Nasal consonant|Nasal]]
| style="background-color: #ccf" | {{IPAslink|m}}<br />ม
| style="background-color: #cfc" | {{IPAslink|n}}<br />ญ, ณ, น, ร, ล, ฬ
|
| style="background-color: #fcc" | {{IPAslink|ŋ}}<br />ง
|
|-
! [[Stop consonant|Plosive]]
| style="background-color: #ccf" | {{IPAslink|p}}<br />บ, ป, พ, ฟ, ภ
| style="background-color: #cfc" | {{IPAslink|t}}<br />จ, ช, ซ, ฌ, ฎ, ฏ, ฐ, ฑ,<br />ฒ, ด, ต, ถ, ท, ธ, ศ, ษ, ส
|
| style="background-color: #fcc" | {{IPAslink|k}}<br />ก, ข, ค, ฆ
| style="background-color: #ccc" | {{IPAslink|ʔ}}{{efn|The glottal plosive appears at the end when no final follows a short vowel}}
|-
! [[Approximant consonant|Approximant]]
| style="background-color: #cff" | {{IPAslink|w}}<br />ว
|
| style="background-color: #cff" | {{IPAslink|j}}<br />ย
|
|
|}

==== Clusters ====
In Thai, each syllable in a word is articulated independently, so consonants from adjacent syllables (i.e. heterosyllabic) show no sign of articulation as a cluster. Thai has specific [[Phonotactics|phonotactical patterns]] that describe its syllable structure, including tautosyllabic [[consonant cluster]]s, and vowel sequences. In core Thai words (i.e. excluding loanwords), only clusters of two consonants occur, of which there are 11 combinations:
* {{IPA|/kr/}} (กร), {{IPA|/kl/}} (กล), {{IPA|/kw/}} (กว)
* {{IPA|/kʰr/}} (ขร, คร), {{IPA|/kʰl/}} (ขล, คล), {{IPA|/kʰw/}} (ขว, คว)
* {{IPA|/pr/}} (ปร), {{IPA|/pl/}} (ปล)
* {{IPA|/pʰr/}} (พร), {{IPA|/pʰl/}} (ผล, พล)
* {{IPA|/tr/}} (ตร)

The number of clusters increases in loanwords such as {{IPA|/tʰr/}} (ทร) in {{Wikt-lang|th|อินทรา}} ({{IPA|/ʔīn.tʰrāː/}}, from Sanskrit ''indrā'') or {{IPA|/fr/}} (ฟร) in {{Wikt-lang|th|ฟรี}} ({{IPA|/frīː/}}, from English ''free''); however, these usually only occur in initial position, with either {{IPA|/r/}}, {{IPA|/l/}}, or {{IPA|/w/}} as the second consonant sound and not more than two sounds at a time. In addition, ก may be Romanized as "g" and ป as "b" in those specific clusters to distinguish them from the corresponded aspirated stops.

=== Vowels ===
The vowel nuclei of the Thai language are given in the following table. The top entry in every cell is the symbol from the [[help:IPA|International Phonetic Alphabet]], the second entry gives the spelling in the [[Thai script]], where a dash (–) indicates the position of the initial consonant after which the vowel is pronounced. A second dash indicates that a final consonant follows.
[[File:Thai vowel chart (monophthongs).svg|thumb|upright=1.15|Monophthongs of Thai. From {{Harvcoltxt|Tingsabadh|Abramson|1993|p=25}}]]
[[File:Thai vowel chart (diphthongs).png|thumb|upright=1.15|Diphthongs of Thai. From {{Harvcoltxt|Tingsabadh|Abramson|1993|p=25}}]]

{| class="wikitable" style="text-align: center"
|-
!rowspan="2" | 
!colspan=2|[[Front vowel|Front]]
!colspan=2|[[Central vowel|Central]]
!colspan=2|[[Back vowel|Back]]
|- class=small
! short || long ||short || long ||short || long
|-
![[Close vowel|Close]]
|{{IPAslink|i}}<br />&nbsp;-ิ&nbsp;<!-- the &nbsp; is necessary for visibility under Opera -->
|{{IPAslink|iː}}<br />&nbsp;-ี&nbsp;
|{{IPAslink|ɯ}}<br />&nbsp;-ึ&nbsp;
|{{IPAslink|ɯː}}<br />&nbsp;-ื-&nbsp;
|{{IPAslink|u}}<br />&nbsp;-ุ&nbsp;
|{{IPAslink|uː}}<br />&nbsp;-ู&nbsp;
|-
![[Mid vowel|Mid]]
|{{IPAslink|e̞|e}}<br />เ-ะ
|{{IPAslink|e̞|eː}}<br />เ-
|{{IPAslink|ɤ}}<br />เ-อะ
|{{IPAslink|ɤː}}<br />เ-อ
|{{IPAslink|o̞|o}}<br />โ-ะ
|{{IPAslink|o̞|oː}}<br />โ-
|-
![[Open vowel|Open]]
|{{IPAslink|ɛ}}<br />แ-ะ
|{{IPAslink|ɛː}}<br />แ-
|{{IPAslink|ä|a}}<br />-ะ, -ั-
|{{IPAslink|ä|aː}}<br />-า
|{{IPAslink|ɔ}}<br />เ-าะ
|{{IPAslink|ɔː}}<br />-อ
|}

Each vowel quality occurs in [[vowel length|long-short pairs]]: these are distinct [[phoneme]]s forming distinct words in Thai.<ref>{{Harvcoltxt|Tingsabadh|Abramson|1993|p=25}}</ref>

The long-short pairs are as follows:

{|class="wikitable"
|-
!colspan="5"|Long
!colspan="5"|Short
|-
!Thai
!IPA
!colspan=3|Example
!Thai
!IPA
!colspan=3|Example
|-
|–า || {{IPA|/aː/}} || {{Wikt-lang|th|ฝาน}} ||{{IPA|/fǎːn/}} || 'to slice'
|–ะ || {{IPA|/a/}}|| {{Wikt-lang|th|ฝัน}} || {{IPA|/fǎn/}} || 'to dream'
|-
|–ี || {{IPA|/iː/}}|| {{Wikt-lang|th|กรีด}} || {{IPA|/krìːt/}} || 'to cut'
|–ิ || {{IPA|/i/}}|| {{Wikt-lang|th|กริช}} || {{IPA|/krìt/}} || '[[kris]]'
|-
|–ู || {{IPA|/uː/}}|| {{Wikt-lang|th|สูด}} || {{IPA|/sùːt/}} || 'to inhale'
|–ุ || {{IPA|/u/}}|| {{Wikt-lang|th|สุด}} || {{IPA|/sùt/}} || 'rearmost'
|-
|เ– || {{IPA|/eː/}}|| {{Wikt-lang|th|เอน}} || {{IPA|/ʔēːn/}} || 'to recline'
|เ–ะ || {{IPA|/e/}}|| {{Wikt-lang|th|เอ็น}} || {{IPA|/ʔēn/}} || 'tendon, ligament'
|-
|แ–|| {{IPA|/ɛː/}}|| {{Wikt-lang|th|แพ้}} || {{IPA|/pʰɛ́ː/}} || 'to be defeated'
|แ–ะ|| {{IPA|/ɛ/}}|| {{Wikt-lang|th|แพะ}} || {{IPA|/pʰɛ́ʔ/}} || 'goat'
|-
|–ื-|| {{IPA|/ɯː/}}|| {{Wikt-lang|th|คลื่น}} || {{IPA|/kʰlɯ̂ːn/}} || 'wave'
|–ึ || {{IPA|/ɯ/}}|| {{Wikt-lang|th|ขึ้น}} || {{IPA|/kʰɯ̂n/}} || 'to go up'
|-
|เ–อ || {{IPA|/ɤː/}}|| {{Wikt-lang|th|เดิน}} || {{IPA|/dɤ̄ːn/}} || 'to walk'
|เ–อะ || {{IPA|/ɤ/}}|| {{Wikt-lang|th|เงิน}} || {{IPA|/ŋɤ̄n/}} || 'silver'
|-
|โ– || {{IPA|/oː/}}|| {{Wikt-lang|th|โค่น}} || {{IPA|/kʰôːn/}} || 'to fell'
|โ–ะ || {{IPA|/o/}}|| {{Wikt-lang|th|ข้น}} || {{IPA|/kʰôn/}} || 'thick (soup)'
|-
|–อ || {{IPA|/ɔː/}}|| {{Wikt-lang|th|กลอง}} || {{IPA|/klɔ̄ːŋ/}} || 'drum'
|เ–าะ || {{IPA|/ɔ/}}|| {{Wikt-lang|th|กล่อง}} || {{IPA|/klɔ̀ŋ/}} || 'box'
|}

There are also opening and closing [[diphthong]]s in Thai, which {{Harvcoltxt|Tingsabadh|Abramson|1993}} analyze as {{IPA|/Vj/}} and {{IPA|/Vw/}}. For purposes of determining tone, those marked with an asterisk are sometimes classified as long:

{|class="wikitable" style="text-align:center"
|-
!colspan="2"|Long
!colspan="2"|Short
|-
!Thai script
!IPA
!Thai script
!IPA
|-
|–าย
|{{IPA|/aːj/}}
|ไ–<sup>*</sup>, ใ–<sup>*</sup>, ไ–ย, -ัย
|{{IPA|/aj/}}
|-
|–าว
|{{IPA|/aːw/}}
|เ–า<sup>*</sup>
|{{IPA|/aw/}}
|-
|เ–ีย
|{{IPA|/ia/}}
|เ–ียะ
|{{IPA|/iaʔ/}}
|-
|–
|–
|–ิว
|{{IPA|/iw/}}
|-
|–ัว
|{{IPA|/ua/}}
|–ัวะ
|{{IPA|/uaʔ/}}
|-
|–ูย
|{{IPA|/uːj/}}
|–ุย
|{{IPA|/uj/}}
|-
|เ–ว
|{{IPA|/eːw/}}
|เ–็ว
|{{IPA|/ew/}}
|-
|แ–ว
|{{IPA|/ɛːw/}}
|–
|–
|-
|เ–ือ
|{{IPA|/ɯa/}}
|เ–ือะ
|{{IPA|/ɯaʔ/}}
|-
|เ–ย
|{{IPA|/ɤːj/}}
|–
|–
|-
|–อย
|{{IPA|/ɔːj/}}
|–
|–
|-
|โ–ย
|{{IPA|/oːj/}}
|–
|–
|}

Additionally, there are three [[triphthongs]]. For purposes of determining tone, those marked with an asterisk are sometimes classified as long:

{|class="wikitable" style="text-align:center"
|-
!Thai script
!IPA
|-
|เ–ียว*
|{{IPA|/iaw/}}
|-
|–วย*
|{{IPA|/uaj/}}
|-
|เ–ือย*
|{{IPA|/ɯaj/}}
|}

=== Tones ===
{{multiple image|total_width=250
|width1=340 |height1=400 |image1=Mid tone (Thai).svg
|width2=340 |height2=400 |image2=Low tone (Thai).svg
|width3=340 |height3=400 |image3=Falling tone (Thai).svg
|width4=340 |height4=400 |image4=High tone (Thai).svg
|width5=340 |height5=400 |image5=Rising tone (Thai).svg
|footer=The five phonemic tones of Standard Thai pronounced with the syllable '/naː/': {{paragraph break}} [[File:Th-Thai tones marked with IPA with na.ogg|center]]
}}
There are five phonemic [[tone (linguistics)|tones]]: mid, low, falling, high, and rising, sometimes referred to in older reference works as ''rectus, gravis, circumflexus, altus,'' and ''demissus,'' respectively.<ref>Frankfurter, Oscar. Elements of Siamese grammar with appendices. American Presbyterian mission press, 1900 [https://books.google.com/books?id=h6U6AAAAMAAJ] (Full text available on Google Books)</ref> The table shows an example of both the [[phoneme|phonemic]] tones and their [[phonetics|phonetic]] realization, in the [[International Phonetic Alphabet|IPA]]. Moren & [[Elizabeth Zsiga|Zsiga]] (2006)<ref>{{Cite journal |last1=Morén |first1=Bruce |last2=Zsiga |first2=Elizabeth |date=2006 |title=The Lexical and Post-Lexical Phonology of Thai Tones* |url=http://link.springer.com/10.1007/s11049-004-5454-y |journal=Natural Language & Linguistic Theory |language=en |volume=24 |issue=1 |pages=113–178 |doi=10.1007/s11049-004-5454-y |s2cid=170764533 |issn=0167-806X|url-access=subscription }}</ref> and Zsiga & Nitisaroj (2007)<ref>{{Cite journal |last1=Zsiga |first1=Elizabeth |last2=Nitisaroj |first2=Rattima |date=2007 |title=Tone Features, Tone Perception, and Peak Alignment in Thai |url=http://journals.sagepub.com/doi/10.1177/00238309070500030301 |journal=Language and Speech |language=en |volume=50 |issue=3 |pages=343–383 |doi=10.1177/00238309070500030301 |pmid=17974323 |s2cid=18595049 |issn=0023-8309|url-access=subscription }}</ref> provide phonetic and phonological analyses of Thai tone realization.
<!-- The whole point of this table is to illustrate phonetic detail of the tones. This doesn't occur anywhere else, and is from the IPA Handbook. -->
[[File:Thai tones.svg|thumb|upright=1.15|Thai language tone chart]]

Notes:
#Five-level tone value: Mid [33], Low [21], Falling [41], High [45], Rising [214]. Traditionally, the high tone was recorded as either [44] or [45]. This remains true for the older generation, but the high tone is changing to [334] among youngsters.<ref>Teeranon, Phanintra. (2007). [http://www.skase.sk/Volumes/JTL10/pdf_doc/1.pdf "The change of Standard Thai high tone: An acoustic study and a perceptual experiment"]. ''SKASE Journal of Theoretical Linguistics, 4''(3), 1–16.</ref><ref>Thepboriruk, Kanjana. (2010). [https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxzZWFsc2pvdXJuYWx8Z3g6NDljZWJlMjUzMGE0NGYyMw "Bangkok Thai Tones Revisited"]. ''Journal of the Southeast Asian Linguistics Society, 3''(1), 86–105.</ref>
#For the diachronic changes of tone value, see Pittayaporn (2007).<ref>Pittayaporn, Pittayawat. (2007). [https://web.archive.org/web/20191204144531/https://pdfs.semanticscholar.org/4b67/bdd99e7a42c241f4fee6edc93f4f17e54ce8.pdf "Directionality of Tone Change"]. ''Proceedings of the 16th International Congress of Phonetic Sciences (ICPhS XVI)''.</ref>
#The full complement of tones exists only in so-called "live syllables", those that end in a long vowel or a [[sonorant]] ({{IPA|/m/, /n/, /ŋ/, /j/, /w/}}).
#For "dead syllables", those that end in a plosive ({{IPA|/p/, /t/, /k/}}) or in a short vowel, only three tonal distinctions are possible: low, high, and falling. Because syllables analyzed as ending in a short vowel may have a final [[glottal stop]] (especially in slower speech), all "dead syllables" are phonetically [[Checked tone|checked]], and have the reduced tonal inventory characteristic of checked syllables.

==== Unchecked syllables ====
{| class=wikitable
|-
! scope="col" | Tone
! scope="col" | Thai
! scope="col" | Example
! scope="col" | Phonemic
! scope="col" | Phonetic
! scope="col" | Gloss
|-
| Mid
| {{lang|th|สามัญ}}
| {{lang|th|คา}}
| {{IPA|/kʰāː/}}
| {{IPA|[kʰäː˧]}}
| 'stick'
|-
| Low
| {{lang|th|เอก}}
| {{lang|th|ข่า}}
| {{IPA|/kʰàː/}}
| {{IPA|[kʰäː˨˩]}} or {{IPA|[kʰäː˩]}}
| '[[galangal]]'
|-
| Falling
| {{lang|th|โท}}
| {{lang|th|ค่า}}
| {{IPA|/kʰâː/}}
| {{IPA|[kʰäː˦˩]}}
| 'value'
|-
| High
| {{lang|th|ตรี}}
| {{lang|th|ค้า}}
| {{IPA|/kʰáː/}}
| {{IPA|[kʰäː˦˥]}} or {{IPA|[kʰäː˥]}}
| 'to trade'
|-
| Rising
| {{lang|th|จัตวา}}
| {{lang|th|ขา}}
| {{IPA|/kʰǎː/}}
| {{IPA|[kʰäː˨˩˦]}} or {{IPA|[kʰäː˨˦]}}
| 'leg'
|}

==== Checked syllables ====

{| class=wikitable
|-
! scope="col" | Tone
! scope="col" | Thai
! scope="col" | Example
! scope="col" | Phonemic
! scope="col" | Phonetic
! scope="col" | Gloss
|-
| Low (short vowel)
| {{lang|th|เอก}}
| {{lang|th|หมัก}}
| {{IPA|/màk/}}
| {{IPA|[mäk̚˨˩]}}
| 'marinate'
|-
| Low (long vowel)
| {{lang|th|เอก}}
| {{lang|th|หมาก}}
| {{IPA|/màːk/}}
| {{IPA|[mäːk̚˨˩]}}
| '[[areca]] nut, areca palm, [[betel]], fruit'
|-
| High
| {{lang|th|ตรี}}
| {{lang|th|มัก}}
| {{IPA|/mák/}}
| {{IPA|[mäk̚˦˥]}}
| 'habitually, likely to'
|-
| Falling
| {{lang|th|โท}}
| {{lang|th|มาก}}
| {{IPA|/mâːk/}}
| {{IPA|[mäːk̚˦˩]}}
| 'a lot, abundance, many'
|}
In some English [[loanword]]s, closed syllables with a long vowel ending in an obstruent sound have a high tone, and closed syllables with a short vowel ending in an obstruent sound have a falling tone.
{| class=wikitable
|-
! scope="col" | Tone
! scope="col" | Thai
! scope="col" | Example
! scope="col" | Phonemic
! scope="col" | Phonetic
! scope="col" | Gloss
|-
| High
| {{lang|th|ตรี}}
| {{lang|th|มาร์ก}}
| {{IPA|/máːk/}}
| {{IPA|[mäːk̚˦˥]}}
| 'Marc, Mark'
|-
| High
| {{lang|th|ตรี}}
| {{lang|th|ชาร์จ}}
| {{IPA|/tɕʰáːt/}}
| {{IPA|[tɕʰäːt̚˦˥]}}
| 'charge'
|-
| Falling
| {{lang|th|โท}}
| {{lang|th|เมกอัป}}
| {{IPA|/méːk.ʔâp/}}
| {{IPA|[meːk̚˦˥.ʔäp̚˦˩]}}
| 'make-up'
|-
| Falling
| {{lang|th|โท}}
| {{lang|th|แร็กเกต}}
| {{IPA|/rɛ́k.kêt/}}
| {{IPA|[rɛk̚˦˥.ket̚˦˩]}}
| 'racket'
|}

== Grammar ==
From the perspective of [[linguistic typology]], Thai can be considered to be an [[analytic language]]. The [[word order]] is [[subject–verb–object]],<ref>{{Cite book|last=Warotamasikkhadit|first=Udom|url=https://wals.info/refdb/record/Warotamasikkhadit-1972|title=Thai Syntax|date=1972|publisher=Mouton.|location=The Hague}}</ref> although the subject is often [[Pro-drop language|omitted]]. Additionally, Thai is an isolating language lacking any form of inflectional morphology whatsoever.<ref name=":2">{{Citation|last=Bisang|first=W.|title=Verb serialisation, grammaticalisation, and attractor positions in Chinese, Hmong, Vietnamese, Thai and Khmer|date=1991|url=https://wals.info/refdb/record/Bisang-1991|work=Partizipation: das sprachliche Erfassen von Sachverhalten|pages=509–562|place=Tübingen|publisher=Narr|access-date=2021-05-02}}</ref> Thai pronouns are selected according to the gender and relative status of speaker and audience.

=== Adjectives and adverbs ===
There is no morphological distinction between [[adverbs]] and [[adjectives]]. Many words can be used in either function. They follow the word they modify, which may be a noun, verb, or another adjective or adverb.

{{fs interlinear|lang=th|glossing4=yes|indent=3
|คน อ้วน
|khon uan
|/{{IPA|kʰōn}} {{IPA|ʔûa̯n}}/
|'a fat person'}}

{{fs interlinear|lang=th|glossing4=yes|indent=3
|คน ที่ อ้วน เร็ว
|khon thi uan reo
|/{{IPA|kʰōn}} {{IPA|tʰîː}} {{IPA|ʔûa̯n}} {{IPA|rēw}}/
|'a person who becomes fat quickly'}}

[[Comparison (grammar)|Comparatives]] take the form "A X {{lang|th|กว่า}} B" ({{lang|th-Latn|kwa}}, {{IPA|/kwàː/}}), 'A is more X than B'. The [[superlative]] is expressed as "A X {{lang|th|ที่สุด}}" ({{lang|th-Latn|thi sut}}, {{IPA|/tʰîː sùt/}}), 'A is most X'.

{{fs interlinear|lang=th|glossing4=yes|indent=3
|เขา อ้วน '''กว่า''' ฉัน
|khao uan '''kwa''' chan
|/{{IPA|kʰǎw}} {{IPA|ʔûa̯n}} '''{{IPA|kwàː}}''' {{IPA|tɕʰǎn}}/
|'S/he is fatter than me.'}}

{{fs interlinear|lang=th|glossing4=yes|indent=3
|เขา อ้วน '''ที่สุด'''
|khao uan {'''thi sut'''}
|/{{IPA|kʰǎw}} {{IPA|ʔûa̯n}} '''{{IPA|tʰîː sùt}}'''/
|'S/he is the fattest (of all).'}}

Adjectives in Thai can be used as [[Stative verb|complete predicates]]. Because of this, many words used to indicate tense in verbs (see Verbs:Tense below) may be used to describe adjectives.

{{fs interlinear|lang=th|glossing4=yes|indent=3
|ฉัน หิว
|chan hio
|/{{IPA|tɕʰǎn}} {{IPA|hǐw}}/
|'I am hungry.'}}

{{fs interlinear|lang=th|glossing4=yes|indent=3
|ฉัน '''จะ''' หิว
|chan '''cha''' hio
|/{{IPA|tɕʰǎn}} '''{{IPA|tɕàʔ}}''' {{IPA|hǐw}}/
|'I will be hungry.'}}

{{fs interlinear|lang=th|glossing4=yes|indent=3
|ฉัน '''กำลัง''' หิว
|chan '''kamlang''' hio
|/{{IPA|tɕʰǎn}} '''{{IPA|kām.lāŋ}}''' {{IPA|hǐw}}/
|'I am hungry right now.'}}

{{fs interlinear|lang=th|glossing4=yes|indent=3
|ฉัน หิว '''แล้ว'''
|chan hio '''laeo'''
|/{{IPA|tɕʰǎn}} {{IPA|hǐw}} '''{{IPA|lɛ́ːw}}'''/
|'I am already hungry.'}}

:* '''Remark''' {{lang|th|ฉันหิวแล้ว}} mostly means 'I am hungry right now' because normally, {{lang|th|แล้ว}} ({{IPA|/lɛ́ːw/}}) marks the change of a state, but {{lang|th|แล้ว}} has many other uses as well. For example, in the sentence, {{lang|th|แล้วเธอจะไปไหน}} ({{IPA|/lɛ́ːw tʰɤ̄ː tɕàʔ pāj nǎj/}}): 'So where are you going?', {{lang|th|แล้ว}} ({{IPA|/lɛ́ːw/}}) is used as a discourse particle.

=== Verbs ===
[[Verb]]s do not [[inflected language|inflect]]. They do not change with person, tense, voice, mood, or number; nor are there any [[participles]]. The language being analytic and [[Grammatical case|case]]-less, the relationship between subject, direct and indirect object is conveyed through word order and [[auxiliary verb]]s. [[Transitive verb|Transitive]] verbs follow the pattern ''subject-verb-object''.

{{fs interlinear|lang=th|indent=3|glossing4=yes
|ฉัน ตี เขา
|chan ti khao
|/{{IPA|tɕʰǎn}} {{IPA|tīː}} {{IPA|kʰǎw}}/
|1SG hit 3SG
|'I hit him.'}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา ตี ฉัน
|khao ti chan
|/{{IPA|kʰǎw}} {{IPA|tīː}} {{IPA|tɕʰǎn}}/
|3SG hit 1SG
|'S/He hit me.'}}

In order to convey [[Tense–aspect–mood|tense, aspect and mood]] (TAM), the Thai verbal system employs auxiliaries and [[Serial verb construction|verb serialization]].<ref name=":3">{{Citation |last1=Jenny |first1=Mathias |title=The aspect system of Thai |date=2001 |url=https://www.zora.uzh.ch/id/eprint/110203/ |work=Aktionsart and Aspectotemporality in non-European languages |pages=97–140 |place=Zürich |publisher=Seminar für Allgemeine Sprachwissenschaft, Universität Zürich |isbn=978-3-9521010-8-7 |access-date=2021-05-02 |last2=Ebert |first2=Karen H. |last3=Zúñiga |first3=Fernando }}</ref><ref name=":2" /> TAM markers are however not obligatory and often left out in colloquial use. In such cases, the precise meaning is determined through context.<ref name=":3" /> This results in sentences lacking both TAM markers and overt context being ambiguous and subject to various interpretations.

{{fs interlinear|lang=th|indent=3|glossing4=yes
|ฉัน กิน ที่ นั่น
|chan kin thi nan
|/{{IPA|tɕʰǎn}} {{IPA|kīn}} {{IPA|tʰîː}} {{IPA|nân}}/
|'I eat there.'}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|ฉัน กิน ที่ นั่น เมื่อวาน
|chan kin thi nan mueawan
|/{{IPA|tɕʰǎn}} {{IPA|kīn}} {{IPA|tʰîː}} {{IPA|nân}} {{IPA|mɯ̂a̯.wāːn}}/
|'I ate there yesterday.'}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|ฉัน จะ กิน ที่ นั่น พรุ่งนี้
|chan cha kin thi nan phrungni
|/{{IPA|tɕʰǎn}} {{IPA|tɕàʔ}} {{IPA|kīn}} {{IPA|thîː}} {{IPA|nân}} {{IPA|pʰrûŋ.níː}}/
|'I'll eat there tomorrow.'}}

The sentence {{lang|th-Latn|chan kin thi nan}} can thus be interpreted as 'I am eating there', 'I eat there habitually', 'I will eat there' or 'I ate there'.  Aspect markers in Thai have been divided into four distinct groups based on their usage.<ref name=":3" /> These markers could appear either before or after the verb. The following list describes some of the most commonly used aspect markers. A number of these aspect markers are also full verbs on their own and carry a distinct meaning. For example {{lang|th-Latn|yu}} ({{lang|th|อยู่}}) as a full verb means 'to stay, to live or to remain at'. However, as an auxiliary it can be described as a ''temporary aspect'' or ''continuative marker''.<ref name=":3" />

* [[Imperfective aspect|Imperfective]]
** {{lang|th|อยู่}} {{lang|th-Latn|yu}} {{IPA|/jùː/}}
** {{lang|th|ไป}} {{lang|th-Latn|pai}} {{IPA|/pāj/}}
** {{lang|th|ยัง}} {{lang|th-Latn|yang}} {{IPA|/jāŋ/}}
** {{lang|th|กำลัง}} {{lang|th-Latn|kamlang}} {{IPA|/kām.lāŋ/}}
** {{lang|th|เคย}} {{lang|th-Latn|khoey}} {{IPA|/kʰɤ̄ːj/}}
* [[Perfective aspect|Perfective]]
** {{lang|th|ได้}} {{lang|th-Latn|dai}} {{IPA|/dâːj/}}
* [[Perfect aspect|Perfect]]
** {{lang|th|แล้ว}} {{lang|th-Latn|laeo}} {{IPA|/lɛ́ːw/}}
** {{lang|th|มา}} {{lang|th-Latn|ma}} {{IPA|/māː/}}
* [[Prospective aspect|Prospective]]/[[Future tense|Future]]
** {{lang|th|จะ}} {{lang|th-Latn|cha}} {{IPA|/tɕàʔ/}}

The imperfective aspect marker {{lang|th|กำลัง}} ({{lang|th-Latn|kamlang}}, {{IPA|/kām lāŋ/}}, currently) is used before the verb to denote an ongoing action (similar to the ''-ing'' suffix in English). {{lang|th-Latn|Kamlang}} is commonly interpreted as a [[progressive aspect|progressive]] aspect marker.<ref name=":4">{{Cite book |last=Boonyapatipark |first=Tasanalai |url=https://books.google.com/books?id=rPRyuAAACAAJ |title=A study of aspect in Thai |date=1983 |publisher=University of London |language=en }}</ref><ref>{{Cite journal |last1=Koenig |first1=Jean-Pierre |last2=Muansuwan |first2=Nuttanart |date=2005 |title=The Syntax of Aspect in Thai |url=https://www.jstor.org/stable/4048104 |journal=Natural Language & Linguistic Theory |volume=23 |issue=2 |pages=335–380 |doi=10.1007/s11049-004-0488-8 |jstor=4048104 |s2cid=170429648 |issn=0167-806X |url-access=subscription }}</ref> Similarly, {{lang|th|อยู่}} ({{lang|th-Latn|yu}}, {{IPA|/jùː/}}) is a post-verbal aspect marker which corresponds to the continuative or temporary aspect.<ref name=":3" />

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''กำลัง''' วิ่ง
|khao '''kamlang''' wing
|/{{IPA|kʰǎw}} '''{{IPA|kām.lāŋ}}''' {{IPA|wîŋ}}/
|}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา วิ่ง '''อยู่'''
|khao wing '''yu'''
|/{{IPA|kʰǎw}} {{IPA|wîŋ}} '''{{IPA|jùː}}'''/
|}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''กำลัง''' วิ่ง '''อยู่'''
|khao '''kamlang''' wing '''yu'''
|/{{IPA|kʰǎw}} '''{{IPA|kām.lāŋ}}''' {{IPA|wîŋ}} '''{{IPA|jùː}}'''/
|'He is running.'}}

Comparably {{lang|th|ยัง}} ({{lang|th-Latn|yang}}, {{IPA|/jāŋ/}}, still) which is used in an incompleted action, and usually cognates in phrase with {{lang|th-Latn|yu}} ({{lang|th|อยู่}}) or any second marker in common use.

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''ยัง''' เขียน '''อยู่'''
|khao '''yang''' khian '''yu'''
|/{{IPA|kʰǎw}} '''{{IPA|jāŋ}}''' {{IPA|kʰǐa̯n}} '''{{IPA|jùː}}'''/
|He is still writing.}}

The marker {{lang|th|ได้}} ({{lang|th-Latn|dai}}, {{IPA|/dâːj/}}) is usually analyzed as a past tense marker when it occurs before the verb.<ref name=":2" /> As a full verb, {{lang|th-Latn|dai}} means 'to get or receive'. However, when used after a verb, {{lang|th-Latn|dai}} takes on a meaning of potentiality or successful outcome of the main verb.<ref name=":3" />

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|เขา '''ได้''' ไป เที่ยว เมือง ลาว
|khao '''dai''' pai thiao mueang lao
|/{{IPA|kʰǎw}} '''{{IPA|dâːj}}''' {{IPA|pāj}} {{IPA|tʰîa̯w}} {{IPA|mɯ̄aŋ}} {{IPA|lāːw}}/
|He visited Laos. (Past/Perfective)}}

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|เขา ตี '''ได้'''
|khao ti '''dai'''
|/{{IPA|kʰǎw}} {{IPA|tīː}} '''{{IPA|dâːj}}'''/
|3SG hit '''POT'''
|'He is/was allowed to hit' or 'He is/was able to hit.' (Potentiality)}}

{{lang|th|แล้ว}} ({{lang|th-Latn|laeo}}, {{IPA|/lɛ́ːw/}}; 'already') is treated as a marker indicating the [[perfect (grammar)|perfect]] aspect.<ref name=":4" /> That is to say, {{lang|th-Latn|laeo}} marks the event as being completed at the time of reference. {{lang|th-Latn|Laeo}} has two other meanings in addition to its use as a TAM marker. {{lang|th-Latn|Laeo}} can either be a conjunction for sequential actions or an archaic word for 'to finish'.

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''ได้''' กิน
|khao '''dai''' kin
|/{{IPA|kʰǎw}} '''{{IPA|dâːj}}''' {{IPA|kīn}}/
|3SG '''PST''' eat
|He ate.}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา กิน '''แล้ว'''
|khao kin '''laeo'''
|/{{IPA|kʰǎw}} {{IPA|kīn}} '''{{IPA|lɛ́ːw}}'''/
|3SG eat '''PRF'''
|He has eaten.}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''ได้''' กิน '''แล้ว'''
|khao '''dai''' kin '''laeo'''
|/{{IPA|kʰǎw}} '''{{IPA|dâːj}}''' {{IPA|kīn}} '''{{IPA|lɛ́ːw}}'''/
|3SG '''PST''' eat '''PRF'''
|He's already eaten.}}

[[Future tense|Future]] can be indicated by {{lang|th|จะ}} ({{lang|th-Latn|cha}}, {{IPA|/tɕàʔ/}}; 'will') before the verb or by a time expression indicating the future. For example:

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|เขา '''จะ''' วิ่ง
|khao '''cha''' wing
|/{{IPA|kʰǎw}} '''{{IPA|tɕàʔ}}''' {{IPA|wîŋ}}/
|3SG '''FUT''' run
|'He will run' or 'He is going to run.'}}

[[Dative case|Dative marker]] {{lang|th|ให้}} ({{lang|th-Latn|hai}}, {{IPA|/hâj/}}; 'give') often used in a sentence as prepositional or double objects.<ref>{{Cite web |title=The Acquisition Of Dative Constructions By Thai |url=http://ethesisarchive.library.tu.ac.th/thesis/2017/TU_2017_5521320084_8564_9178.pdf}}</ref>

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา อ่าน หนังสือ '''ให้'''
|khao an {nangsue} '''hai'''
|/{{IPA|kʰǎw}} {{IPA|ʔàːn}} {{IPA|nǎŋ.sɯ̌ː}} '''{{IPA|hâj}}'''/
|3SG read book '''DAT'''
|'He reads book for (us).'}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''ให้''' อ่าน หนังสือ
|khao '''hai''' an {nangsue}
|/{{IPA|kʰǎw}} '''{{IPA|hâj}}''' {{IPA|ʔàːn}} {{IPA|nǎŋ.sɯ̌ː}}/
|3SG '''DAT''' read book
|'He obligates (us) to read book.'}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|เขา '''ให้''' หนังสือ นักเรียน
|khao '''hai''' {nangsue} {nak rian}
|/{{IPA|kʰǎw}} '''{{IPA|hâj}}''' {{IPA|nǎŋ.sɯ̌ː}} {{IPA|nák ria̯n}}/
|3SG '''DAT''' book student
|'He gives book to student.'}}

The [[passive voice]] is indicated by the insertion of {{lang|th|ถูก}} ({{lang|th-Latn|thuk}}, {{IPA|/tʰùːk/}}) before the verb. For example:

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|เขา '''ถูก''' ตี
|khao '''thuk''' ti
|/{{IPA|kʰǎw}} '''{{IPA|tʰùːk}}''' {{IPA|tīː}}/
|3SG '''PASS''' hit
|'He got hit.'}}
::This describes an action that is out of the receiver's control and, thus, conveys suffering.

[[Negation (rhetoric)|Negation]] is indicated by placing {{lang|th|ไม่}} ({{lang|th-Latn|mai}}, {{IPA|/mâj/}}; not) before the verb.
* {{lang|th|เขาไม่ตี}}, ({{lang|th-Latn|khao mai ti}}) 'He is not hitting' or 'He doesn't hit'.

Thai exhibits [[serial verb construction]]s, where verbs are strung together. Some word combinations are common and may be considered set phrases.

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|เขา ไป กิน ข้าว
|khao pai kin khao
|/{{IPA|kʰǎw}} {{IPA|pāj}} {{IPA|kīn}} {{IPA|kʰâːw}}/
|he go eat rice
|'He went out to eat'}}

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|ฉัน ฟัง ไม่ เข้าใจ
|chan fang mai {khao chai}
|/{{IPA|tɕʰǎn}} {{IPA|fāŋ}} {{IPA|mâj}} {{IPA|kʰâw tɕāj}}/
|I listen not understand
|'I don't understand what was said'}}

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|เข้า มา
|khao ma
|/{{IPA|kʰâw}} {{IPA|māː}}/
|enter come
|'Come in'}}

{{fs interlinear|lang=th|glossing4=yes|number=ex:
|ออก ไป!
|ok pai
|/{{IPA|ʔɔ̀ːk}} {{IPA|pāj}}/
|exit go
|'Leave!' or 'Get out!'}}

=== Nouns ===
[[Noun]]s are [[uninflected word|uninflected]] and have no [[grammatical gender|gender]]; there are no [[article (grammar)|articles]]. Thai nouns are [[bare nouns]] and can be interpreted as singular, plural, definite or indefinite.<ref name=":0">{{Cite thesis |last=Jenks |first=Peter |date=2011 |title=The Hidden Structure of Thai Noun Phrases |type=PhD dissertation |publisher=Harvard University |url=http://www.linguistics.berkeley.edu/~jenks/Research_files/Jenks_2011.pdf |archive-url=https://web.archive.org/web/20150503175806/http://linguistics.berkeley.edu/~jenks/Research_files/Jenks_2011.pdf |archive-date=2015-05-03 |url-status=live |isbn=978-1-267-10767-1 |s2cid=118127511 |id={{ProQuest|915016895}} }}</ref> Some specific nouns are [[reduplication|reduplicated]] to form [[collective number|collectives]]: {{lang|th|เด็ก}} ({{lang|th-Latn|dek}}, 'child') is often repeated as {{lang|th|เด็ก ๆ}} ({{lang|th-Latn|dek dek}}) to refer to a group of children. The word {{lang|th|พวก}} ({{lang|th-Latn|phuak}}, {{IPA|/pʰûa̯k/}}) may be used as a prefix of a noun or pronoun as a collective to pluralize or emphasise the following word. ({{lang|th|พวกผม}}, {{lang|th-Latn|phuak phom}}, {{IPA|/pʰûa̯k pʰǒm/}}, 'we', masculine; {{lang|th|พวกเรา}} {{lang|th-Latn|phuak rao}}, {{IPA|/pʰûa̯k rāw/}}, emphasised 'we'; {{lang|th|พวกหมา}} {{lang|th-Latn|phuak ma}}, '(the) dogs'). Plurals are expressed by adding [[classifier (linguistics)|classifiers]], used as [[measure word]]s ({{lang|th|ลักษณนาม}}), in the form of noun-number-classifier:

{{fs interlinear|lang=th|indent=3|glossing4=yes
|ครู ห้า คน
|khru ha khon
|/{{IPA|kʰrūː}} {{IPA|hâː}} {{IPA|kʰōn}}/
|teacher five person
|"five teachers"}}

While in English, such classifiers are usually absent ("four chairs") or optional ("two bottles of beer" ''or'' "two beers"), a classifier is almost always used in Thai (hence "chair four item" and "beer two bottle").

[[Possessive case|Possession]] in Thai is indicated by adding the word {{lang|th|ของ}} ({{lang|th-Latn|khong}}) in front of the [[noun]] or [[pronoun]], but it may often be omitted. For example:

{{Col-begin}}
{{Col-2}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|ลูก ของ แม่
|luk khong mae
|/{{IPA|lûːk}} {{IPA|kʰɔ̌ːŋ}} {{IPA|mɛ̂ː}}/
|child {belonging to} mother
|"mother's child"}}
{{Col-2}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|นา อา
|na a
|/{{IPA|nāː}} {{IPA|ʔāː}}/
|field uncle
|"uncle's field"<ref>{{Cite web|url=http://www.thailanguage.org/thai/grammar.asp|title=Thailanguage.org|access-date=18 September 2010|archive-date=11 November 2005|archive-url= https://web.archive.org/web/20051111090104/http://www.thailanguage.org/thai/grammar.asp|url-status=usurped}}</ref>}}
{{Col-end}}

==== Nominal phrases ====
[[Noun phrase|Nominal phrases]] in Thai often use a special class of words [[classifier (linguistics)|classifiers]]. As previously mentioned, these classifiers are obligatory for noun phrases containing numerals e.g.

{{fs interlinear|lang=th|indent=3|glossing4=yes
|ผู้หญิง สอง คน
|phuying song khon
|/{{IPA|pʰûː.jǐŋ}} {{IPA|sɔ̌ːŋ}} {{IPA|kʰōn}}/
|woman two CL
|two women<ref name=":1" />}}

Unlike any numeral, {{lang|th|หนึ่ง}} ('one') can mark on both positions of classifier, but in different functions. The post-head one potentially marks a referent as [[indefinite article]].

{{Col-begin}}
{{Col-2}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|แก้ว หนึ่ง ใบ
|kaew neung bai
|/{{IPA|kɛ̂ːw}}  {{IPA|nɯ̀ŋ}} {{IPA|bāj}}/
|glass one CL
|"one glass" (quantificational)}}
{{Col-2}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|แก้ว ใบ หนึ่ง
|kaew bai neung
|/{{IPA|kɛ̂ːw}} {{IPA|bāj}} {{IPA|nɯ̀ŋ}}/
|glass CL one
|"a glass" (referential)}}
{{Col-end}}

In the previous example {{lang|th-Latn|khon}} ({{lang|th|คน}}) acts as the classifier in the nominal phrase. This follows the form of noun-cardinal-classifier mentioned above. Classifiers are also required to form quantified noun phrases in Thai with some quantifiers such as {{lang|th|ทุก}} ('all'), {{lang|th|บาง}} ('some'). The examples below are demonstrated using the classifier {{lang|th-Latn|khon}}, which is used for people.

{{Col-begin}}
{{Col-2}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|{นักเรียน} ทุก คน
|{nak rian} thuk khon
|/{{IPA|nák rīa̯n}} {{IPA|tʰúk}} {{IPA|kʰōn}}/
|student every CL
|"every student"}}
{{Col-2}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|ครู บาง คน
|khru bang khon
|/{{IPA|kʰrūː}} {{IPA|bāːŋ}} {{IPA|kʰōn}}/
|teacher some CL
|"some teacher"}}
{{Col-end}}

However, classifiers are not utilized for negative quantification. Negative quantification is expressed by the pattern {{lang|th|ไม่มี}} ({{lang|th-Latn|mai mi}}, {{IPA|/mâj mīː/}}) + NOUN.

=== Demonstratives ===
Thai has three of its distinctions. ''Proximal'' {{lang|th|นี่}} ({{lang|th-Latn|ni}}, {{IPA|/nîː/}}; 'this/these'), ''medial'' {{lang|th|นั่น}} ({{lang|th-Latn|nan}}, {{IPA|/nân/}}; 'that/those'), and ''distal'' {{lang|th|โน่น}} ({{lang|th-Latn|non}}, {{IPA|/nôːn/}}; 'that/those over there') which is rarely used.

It also has different usage of distinguishing the demonstratives by changing tones. In which the pronoun itself used for ''{{lang|th|นี่}} ({{lang|th-Latn|ni}}, {{IPA|/nîː/}})''; while ''{{lang|th|นี้}} ({{lang|th-Latn|ni}}, {{IPA|/níː}})'' refers to be modifier placed after the noun, prepositions, classifiers, etc. For example:

{{fs interlinear|lang=th|indent=3|glossing4=yes
|'''นี่''' คือ โต๊ะ ใหม่
|'''ni''' kheu to mai
|/'''{{IPA|nîː}}''' {{IPA|kʰɯ̄ː}} {{IPA|tóʔ}} {{IPA|màj}}/
|'''this'''-PRO be table new
|"this is a new table"}}

{{fs interlinear|lang=th|indent=3|glossing4=yes
|วาง ถ้วย บน '''นั้น'''
|wang thuai bon '''nan'''
|/{{IPA|wāːŋ}} {{IPA|tʰûa̯j}} {{IPA|bōn}} '''{{IPA|nán}}'''/ 
|{put down} bowl on '''that'''-PREP
|"put a bowl on there"}}

Following the word {{lang|th|ไหน}} ({{lang|th-Latn|nai}}, {{IPA|/nǎj/}}) which plays role as interrogative determiner or pronoun.

{{Col-begin}}
{{Col-3}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|แมว ตัว ไหน
|maew tua nai
|/{{IPA|mɛ̄ːw}} {{IPA|tūa̯}} {{IPA|nǎj}}/ 
|cat CL INT
|"which cat?"}}
{{Col-3}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|จอด ที่ ไหน
|joat thi nai
|/{{IPA|t͡ɕɔ̀ːt}} {{IPA|tʰîː}} {{IPA|nǎj}}/ 
|park PREP INT
|"where to park?"}}
{{Col-3}}
{{fs interlinear|lang=th|indent=3|glossing4=yes
|พัก ตอน ไหน
|phak toan nai
|/{{IPA|pʰák}} {{IPA|tɔ̄ːn}} {{IPA|nǎj}}/ 
|rest since INT
|"when to rest?"}}
{{Col-end}}

The syntax for demonstrative phrases, however, differ from that of cardinals and follow the pattern ''noun-classifier-demonstrative''. For example, the noun phrase "this dog" would be expressed in Thai as {{lang|th|หมาตัวนี้}} (literally 'dog (classifier) this').<ref name=":1">{{Cite book|last=Smyth|first=David |title=Thai|date=2014|publisher=Taylor and Francis|isbn=978-1-317-97457-4|edition=2nd |location=Hoboken|oclc=879025983}}</ref>

=== Pronouns ===
Subject [[pronoun]]s are [[pronoun avoidance|often omitted]], with [[nickname]]s used where English would use a pronoun. See [[Thai name#Nicknames]] for more details. Pronouns, when used, are ranked in [[Thai honorifics|honorific registers]], and may also make a [[T–V distinction#Thai|T–V distinction]] in relation to [[kinship terminology|kinship]] and [[social status]]. Specialised pronouns are used for royalty, and for Buddhist monks. The following are appropriate for conversational use:

{|class="wikitable"
|-
!Word || [[Royal Thai General System of Transcription|RTGS]] || [[Help:IPA|IPA]] || Meaning
|-
| {{lang|th|ข้าพเจ้า}}
| {{lang|th|khaphachao}}
| {{IPA|/kʰâː.pʰáʔ.tɕâːw/}}
| I/me (very formal)
|-
| {{lang|th|กระผม}}
| {{lang|th|kraphom}}
| {{IPA|/kràʔ.pʰǒm/}}
| I/me (masculine; formal)
|-
| {{lang|th|ผม}}
| {{lang|th-Latn|phom}}
| {{IPA|/pʰǒm/}}
| I/me (masculine; common)
|-
| {{lang|th|ดิฉัน}}
| {{lang|th-Latn|dichan}}
| {{IPA|/dìʔ.tɕʰǎn/}}
| I/me (feminine; formal)
|-
| {{lang|th|ฉัน}}
| {{lang|th-Latn|chan}}
| {{IPA|/tɕʰǎn/}}
| I/me (mainly used by women; common) Commonly pronounced as {{IPA|[tɕʰán]}}
|-
| {{lang|th|ข้า}}
| {{lang|th-Latn|kha}}
| {{IPA|/kʰâː/}}
| I/me (from high-status to low-status or familiar; informal)
|-
| {{lang|th|กู}}
| {{lang|th-Latn|ku}}
| {{IPA|/kūː/}}
| I/me (impolite/vulgar)
|-
| {{lang|th|หนู}}
| {{lang|th-Latn|nu}}
| {{IPA|/nǔː/}}
| I/me (used by women when speaking to people much older than themselves; informal)<ref>{{Cite web |title=The Many Different Ways To Say "I" |work=Beginner Thai Speaking |date=28 September 2021 |url=https://learnthaiinsingapore.com/the-many-different-ways-to-say-i-in-thai/ |access-date=2021-11-12 |language=en-SG }}</ref>
|-
| {{lang|th|เรา}}
| {{lang|th-Latn|rao}}
| {{IPA|/rāw/}}
| we/us (common), I/me (casual), you (sometimes used but only when older person speaks to younger person)
|-
| {{lang|th|คุณ}}
| {{lang|th-Latn|khun}}
| {{IPA|/kʰūn/}}
| you (common)
|-
| {{lang|th|ท่าน}}
| {{lang|th-Latn|than}}
| {{IPA|/tʰâːn/}}
| you (highly [[honorific]]; formal) Commonly pronounced as {{IPA|[tʰân]}}
|-
| {{lang|th|แก}}
| {{lang|th-Latn|kae}}
| {{IPA|/kɛ̄ː/}}
| you (familiar; informal)<ref>{{Cite web |author=Joanne Tan |title=How to say You in Thai Language |website=Learn Thai in Singapore |url=https://learnthaiinsingapore.com/how-to-say-you-in-thai-language/ }}</ref>
|-
| {{lang|th|เอ็ง}}
| {{lang|th-Latn|eng}}
| {{IPA|/ʔēŋ/}}
| you (from high-status to low-status or familiar; informal)
|-
| {{lang|th|เธอ}}
| {{lang|th-Latn|thoe}}
| {{IPA|/tʰɤ̄ː/}}
| you (informal), she/her (informal)
|-
| {{lang|th|มึง}}
| {{lang|th-Latn|mueng}}
| {{IPA|/mɯ̄ŋ/}}
| you (impolite/vulgar)
|-
| {{lang|th|พี่}}
| {{lang|th-Latn|phi}}
| {{IPA|/pʰîː/}}
| older brother, sister (also used for older acquaintances; common)
|-
| {{lang|th|น้อง}}
| {{lang|th-Latn|nong}}
| {{IPA|/nɔ́ːŋ/}}
| younger brother, sister (also used for younger acquaintances; common)
|-
| {{lang|th|เขา}}
| {{lang|th-Latn|khao}}
| {{IPA|/kʰǎw/}}
| he/him (common), she/her (common) Commonly pronounced as {{IPA|[kʰáw]}}
|-
| {{lang|th|มัน}}
| {{lang|th-Latn|man}}
| {{IPA|/mān/}}
| it, he/she (offensive if used to refer to a person)
|-
|}

The reflexive pronoun is {{lang|th|ตัวเอง}} ({{lang|th-Latn|tua eng}}), which can mean any of: myself, yourself, ourselves, himself, herself, themselves. This can be mixed with another pronoun to create an [[intensive pronoun]], such as {{lang|th|ตัวผมเอง}} ({{lang|th-Latn|tua phom eng}}, lit: I myself) or {{lang|th|ตัวคุณเอง}} ({{lang|th-Latn|tua khun eng}}, lit: you yourself). Thai also does not have a separate [[possessive pronoun]]. Instead, possession is indicated by the particle {{lang|th|ของ}} ({{lang|th-Latn|khong}}).  For example, "my mother" is {{lang|th|แม่ของผม}} ({{lang|th-Latn|mae khong phom}}, lit: mother of I). This particle is often implicit, so the phrase is shortened to {{lang|th|แม่ผม}} ({{lang|th-Latn|mae phom}}). Plural pronouns can be easily constructed by adding the word {{lang|th|พวก}} ({{lang|th-Latn|phuak}}) in front of a singular pronoun as in {{lang|th|พวกเขา}} ({{lang|th-Latn|phuak khao}}) meaning 'they' or {{lang|th|พวกเธอ}} ({{lang|th-Latn|phuak thoe}}) meaning the plural sense of 'you'. The only exception to this is {{lang|th|เรา}} ({{lang|th-Latn|rao}}), which can be used as singular (informal) or plural, but can also be used in the form of {{lang|th|พวกเรา}} ({{lang|th-Latn|phuak rao}}), which is only plural.

Thai has many more pronouns than those listed above. Their usage is full of nuances. For example:

* "{{lang|th|ผม เรา ฉัน ดิฉัน หนู กู ข้า กระผม ข้าพเจ้า กระหม่อม อาตมา กัน ข้าน้อย ข้าพระพุทธเจ้า อั๊ว เขา}}" all translate to "I", but each expresses a different gender, age, politeness, status, or relationship between speaker and listener.
* {{lang|th|เรา}} ({{lang|th-Latn|rao}}) can be first person (I), second person (you), or both (we), depending on the context.
* Children or younger female could use or being referred by word {{lang|th|หนู}} ({{lang|th-Latn|nu}}) when talking with older person. The word {{lang|th|หนู}} could be both feminine first person (I) and feminine second person (you) and also neuter first and neuter second person for children.
** {{lang|th|หนู}} commonly means rat or mouse, though it also refers to small creatures in general.
* The second person pronoun {{lang|th|เธอ}} ({{lang|th-Latn|thoe}}) (lit: you) is semi-feminine. It is used only when the speaker or the listener (or both) are female. Males usually do not address each other by this pronoun.
* Both {{lang|th|คุณ}} ({{lang|th-latn|khun}}) and {{lang|th|เธอ}} ({{lang|th-Latn|thoe}}) are polite neuter second person pronouns.  However, {{lang|th|คุณเธอ}} ({{lang|th-Latn|khun thoe}}) is a feminine derogative third person.
* Instead of a second person pronoun such as {{lang|th|คุณ}} ('you'), it is much more common for unrelated strangers to call each other {{lang|th|พี่ น้อง ลุง ป้า น้า อา ตา}} or {{lang|th|ยาย}} (brother, sister, aunt, uncle, granny).
* To express deference, the second person pronoun is sometimes replaced by a profession, similar to how, in English, presiding judges are always addressed as "your honor" rather than "you".  In Thai, students always address their teachers by {{lang|th|ครู}}, {{lang|th|คุณครู}} or {{lang|th|อาจารย์}} (each meaning 'teacher') rather than {{lang|th|คุณ}} ('you').  Teachers, monks, and doctors are almost always addressed this way.

=== Particles ===
The [[grammatical particle|particles]] are often untranslatable words added to the end of a sentence to indicate respect, a request, encouragement or other moods (similar to the use of [[intonation (linguistics)|intonation]] in English), as well as varying the level of formality. They are not used in elegant (written) Thai. The most common particles indicating respect are {{lang|th|ครับ}} ({{lang|th-Latn|khrap}}, {{IPA|/kʰráp/}}, with a high tone) when the speaker is a man, and {{lang|th|ค่ะ}} ({{lang|th-Latn|kha}}, {{IPA|/kʰâʔ/}}, with a falling tone) when the speaker is a woman. Used in a question or a request, the particle {{lang|th|ค่ะ}} (falling tone) is changed to a {{lang|th|คะ}} (high tone).

Other common particles are:

{|class="wikitable"
|-
! Word
! [[Royal Thai General System of Transcription|RTGS]]
! [[help:IPA|IPA]]
! Meaning
|-
| {{lang|th|จ้ะ}}, {{lang|th|จ้า}} or {{lang|th|จ๋า}}
| {{lang|th-Latn|cha}}
| {{IPA|/tɕâʔ/}}, {{IPA|/tɕâː/}} or {{IPA|/tɕǎː/}}
| indicating emphasis. Used in a less formal context when speaking to friends or someone younger than yourself<ref name=":5">{{Cite web |title=What Do 'krub' And 'ka' Mean In Thai Language & When To Use |date=5 October 2021 |url=https://learnthaiinsingapore.com/what-do-krub-and-ka-mean-in-thai/ |access-date=2021-11-01 |language=en-SG }}</ref>
|-
| {{lang|th|ละ}} or {{lang|th|ล่ะ}}
| {{lang|th-Latn|la}}
| {{IPA|/láʔ/}} or {{IPA|/lâʔ/}}
| indicating emphasis.
|-
| {{lang|th|สิ}} or {{lang|th|ซิ}}
| {{lang|th-Latn|si}}
| {{IPA|/sìʔ/}} or {{IPA|/síʔ/}}
| indicating emphasis or an imperative. It can come across as ordering someone to do something<ref name=":5" />
|-
| {{lang|th|นะ}} or {{lang|th|น่ะ}}
| {{lang|th-Latn|na}}
| {{IPA|/náʔ/}} or {{IPA|/nâʔ/}}
| softening; indicating a request or making your sentence sound more friendly.
|}

== Register ==
Central Thai is composed of several distinct [[register (sociolinguistics)|registers]], forms for different social contexts:
* Street or Common Thai ({{Wikt-lang|th|ภาษาพูด}}, {{lang|th-Latn|phasa phut}}, spoken Thai): informal, without polite terms of address, as used between close relatives and friends.
* Elegant or Formal Thai ({{Wikt-lang|th|ภาษาเขียน}}, {{lang|th-Latn|phasa khian}}, written Thai): official and written version, includes respectful terms of address; used in simplified form in newspapers.
* Rhetorical Thai: used for public speaking.
* Religious Thai: (heavily influenced by [[Sanskrit]] and [[Pāli]]) used when discussing Buddhism or addressing monks.
* Royal Thai ({{lang|th|ราชาศัพท์}}, {{lang|th-Latn|racha sap}}): influenced by [[Khmer language|Khmer]], this is used when addressing members of the [[Royal Family of Thailand|royal family]] or describing their activities. (See {{section link|Monarchy of Thailand|Rachasap}}.)

Most Thais can speak and understand all of these contexts. Street and Elegant Thai are the basis of all conversations.<ref>{{Cite web|url=http://www.studycountry.com/guide/TH-language.htm|title=The Languages spoken in Thailand|website=Studycountry|language=en-US|access-date=2017-12-26}}</ref>{{Citation needed|date=March 2009}} Rhetorical, religious, and royal Thai are taught in schools as part of the national curriculum.

As noted above, Thai has several registers, each having certain usages, such as colloquial, formal, literary, and poetic. Thus, the word 'eat' can be {{lang|th|กิน}} ({{lang|th-Latn|kin}}; common), {{lang|th|แดก}} ({{lang|th-Latn|daek}}; vulgar), {{lang|th|ยัด}} ({{lang|th-Latn|yat}}; vulgar), {{lang|th|บริโภค}} ({{lang|th-Latn|boriphok}}; formal), {{lang|th|รับประทาน}} ({{lang|th-Latn|rapprathan}}; formal), {{lang|th|ฉัน}} ({{lang|th-Latn|chan}}; religious), or {{lang|th|เสวย}} ({{lang|th-Latn|sawoei}}; royal), as illustrated below:
{| class="wikitable"
|-
! "to eat" !! [[International Phonetic Alphabet|IPA]] !! Transliteration !! Usage !! Note
|-
| {{lang|th|กิน}} || {{IPA|/kīn/}} || ''kin'' || common ||
|-
| {{lang|th|แดก}} || {{IPA|/dɛ̀ːk/}} || ''daek'' || vulgar ||
|-
| {{lang|th|ยัด}} || {{IPA|/ját/}} || ''yat'' || vulgar || Original meaning is 'to cram'
|-
|{{lang|th|บริโภค}} || {{IPA|/bɔ̄ː.ríʔ.pʰôːk/}} || ''boriphok'' || formal, literary ||
|-
| {{lang|th|รับประทาน}} || {{IPA|/ráp.pràʔ.tʰāːn/}} || ''rapprathan'' || formal, polite|| Often shortened to {{lang|th|ทาน}} /tʰāːn/.
|-
| {{lang|th|ฉัน}} || {{IPA|/tɕʰǎn/}} || ''chan'' || religious ||
|-
| {{lang|th|เสวย}} || {{IPA|/sàʔ.wɤ̌ːj/}} || ''sawoei'' || royal ||
|}
Thailand also uses the distinctive [[Thai six-hour clock]] in addition to the [[24-hour clock]].

== Vocabulary ==
{{Main|List of loanwords in Thai|List of Thai language idioms}}
Other than [[compound word]]s and words of foreign origin, most words are [[syllable|monosyllabic]].

Chinese-language influence was strong until the 13th century when the use of Chinese characters was abandoned, and replaced by Sanskrit and Pali scripts. However, the vocabulary of Thai retains many words borrowed from [[Middle Chinese]].<ref>{{cite book |first1=Martin |last1=Haspelmath |first2=Uri |last2=Tadmor |title=Loanwords in the World's Languages: A Comparative Handbook |date=2009 |page=611 |quote=Thai is of special interest to lexical borrowing for various reasons. The copious borrowing of basic vocabulary from Middle Chinese and later from Khmer indicates that, given the right sociolinguistic context, such vocabulary is not at all immune }}</ref><ref>{{cite book |first=Harald |last=Haarmann |title=Language in Ethnicity: A View of Basic Ecological Relations |date=1986 |page=165 |quote=In Thailand, for instance, where the Chinese influence was strong until the Middle Ages, Chinese characters were abandoned in written Thai in the course of the thirteenth century. }}</ref><ref>{{cite book |first=Paul A. |last=Leppert |title=Doing Business With Thailand |date=1992 |page=13 |quote=At an early time the Thais used Chinese characters. But, under the influence of Indian traders and monks, they soon dropped Chinese characters in favor of Sanskrit and Pali scripts. }}</ref>

[[Khmer language|Khmer]] was used as a prestige language in the early days of the Thai kingdoms which are believed to have been bilingual societies proficient in Thai and Khmer. There are over 2,500 Thai words derived from [[Khmer language|Khmer]], surpassing the number of [[Tai languages|Tai]] cognates. These Khmer words span across all semantic fields. Thai scholar Uraisi Varasarin classified them into over 200 sub-categories. As a result, it is impossible for Thais, past and present, to engage in a conversation without incorporating Khmer loanwords in any given topic. The influence is particularly preponderant in regard to royal court terminology.<ref name="Wilaiwan">{{cite journal |last1= Khanittanan |first1= Wilaiwan |date= 2004 |title=Khmero-Thai: The Great Change in the History of the Thai Language of the Chao Phraya Basin|journal= Annual Meeting of the Southeast Asian Linguistics Society |volume= 11 |url=http://sealang.net/sala/archives/pdf4/wilaiwan2004khmero.pdf}}</ref>

Later, most vocabulary was borrowed from [[Sanskrit]] and [[Pāli]]; [[Buddhism|Buddhist]] terminology is particularly indebted to these. Indic words have a more formal register, and may be compared to Latin and [[List of English words of French origin|French borrowings in English]]. Since the beginning of the 20th century, however, the [[English language]] has had the greatest influence, especially for scientific, technical, international, and other modern terms.
{| class="wikitable"
|-
! Origin !! Example !! [[International Phonetic Alphabet|IPA]] !! Gloss
|-
| rowspan=4 | [[Tai languages|Native Tai]]
| lang=th | ไฟ
| {{IPA|/fāj/}}
| fire
|-
| lang=th | น้ำ
| {{IPA|/náːm/}}
| water
|-
| lang=th | เมือง
| {{IPA|/mɯ̄aŋ/}}
| town
|-
| lang=th | รุ่งเรือง
| {{IPA|/rûŋ rɯ̄aŋ/}}
| prosperous
|-
| rowspan=4 | Indic sources:<br /> [[Pali language|Pāli]] or [[Sanskrit language|Sanskrit]]
| lang=th | อัคนี (''agni'')
| {{IPA|/ʔàk.kʰáʔ.nīː/}}
| fire
|-
| lang=th | ชล (''jala'')
| {{IPA|/tɕʰōn/}}
| water
|-
| lang=th | ธานี (''dhānī'')
| {{IPA|/tʰāː.nīː/}}
| town
|-
| lang=th | วิโรจน์ (''virocana'')
| {{IPA|/wíʔ.rôːt/}}
| prosperous
|}

=== Arabic-origin ===
{| class="wikitable"
|-
! Arabic words !! Thai rendition !! IPA !! Gloss
|-
| {{lang|ar|الْقُرْآن}} ({{lang|ar-Latn|al-qurʾān}}) or {{lang|ar|قُرْآن}} ({{lang|ar-Latn|qurʾān}})
| {{lang|th|อัลกุรอาน}} or {{lang|th|โกหร่าน}}
| {{IPA|/ʔān kùʔ.ráʔ.ʔāːn/}} or {{IPA|/kōː.ràːn/}}
| [[Quran]]
|-
| {{lang|ar|رجم}} ({{lang|ar-Latn|[[rajm]]}})
| {{lang|th|ระยำ}}
| {{IPA|/ráʔ.jām/}}
| bad, vile (vulgar)
|}

=== Chinese-origin ===
From [[Middle Chinese language|Middle Chinese]] or [[Teochew dialect|Teochew Chinese]].
{| class="wikitable"
|-
! colspan=2 | Chinese words
! Thai rendition !! IPA !! Gloss
|-
| {{wikt-lang|zh|交椅}}
| [[Teochew dialect|Teochew]]: {{lang|nan-Latn|gao<sup>1</sup> in<sup>2</sup>}}
| {{lang|th|เก้าอี้}}
| {{IPA|/kâw.ʔîː/}}
| chair
|-
| {{wikt-lang|zh|粿條}} / {{wikt-lang|zh|粿条}}
| [[Southern Min|Min Nan]]: {{lang|nan-Latn|kóe-tiâu}}
| {{Wikt-lang|th|ก๋วยเตี๋ยว}}
| {{IPA|/kǔaj.tǐaw/}}
| [[rice noodle]]
|-
| {{wikt-lang|zh|姐}}
| [[Hokkien]]: {{lang|nan-Latn|chiá}}/{{lang|nan-Latn|ché}}<br />Teochew: {{lang|nan-Latn|zê<sup>2</sup>/zia<sup>2</sup>}}
| {{lang|th|เจ้}} or {{lang|th|เจ๊}}
| {{IPA|/tɕêː/}} or {{IPA|/tɕéː/}}
| older sister (used in Chinese community in Thailand)
|-
| {{wikt-lang|zh|二}}
| Hokkien: {{lang|nan-Latn|jī}}<br />Teochew: {{lang|nan-Latn|ri<sup>6</sup>}}
| {{lang|th|ยี่}}
| {{IPA|/jîː/}}
| two (archaic, but still used in word {{lang|th|ยี่สิบ}} {{IPA|/jîː sìp/}}; 'twenty')
|-
| {{wikt-lang|zh|豆}}
| [[Middle Chinese]]: {{lang|ltc-Latn|dəu<sup>H</sup>}}
| {{lang|th|ถั่ว}}
| {{IPA|/tʰùa/}}
| bean
|-
| {{wikt-lang|zh|盎}}
| Middle Chinese: {{lang|ltc-Latn|ʔɑŋ<sup>X</sup>}}/{{lang|ltc-Latn|ʔɑŋ<sup>H</sup>}}
| {{lang|th|อ่าง}}
| {{IPA|/ʔàːŋ/}}
| basin
|-
| {{wikt-lang|zh|膠}}
| Middle Chinese: {{lang|ltc-Latn|kˠau}}
| {{lang|th|กาว}}
| {{IPA|/kāːw/}}
| glue
|-
| {{wikt-lang|zh|鯁}}
| Middle Chinese: {{lang|ltc-Latn|kˠæŋ<sup>X</sup>}}
| {{lang|th|ก้าง}}
| {{IPA|/kâːŋ/}}
| fishbone
|-
| {{wikt-lang|zh|坎}}
| Middle Chinese: {{lang|ltc-Latn|kʰʌm<sup>X</sup>}}
| {{lang|th|ขุม}}
| {{IPA|/kʰǔm/}}
| pit
|-
| {{wikt-lang|zh|塗}}
| Middle Chinese: {{lang|ltc-Latn|duo}}/{{lang|ltc-Latn|ɖˠa}}
| {{lang|th|ทา}}
| {{IPA|/tʰāː/}}
| to smear
|-
| {{wikt-lang|zh|退}}
| Middle Chinese: {{lang|ltc-Latn|tʰuʌi<sup>H</sup>}}
| {{lang|th|ถอย}}
| {{IPA|/tʰɔ̌j/}}
| to step back
|}

=== English-origin ===
{| class="wikitable"
|-
! English words !! Thai rendition !! IPA !! Remark
|-
| apple
| {{lang|th|แอปเปิล}}
| {{IPA|/ʔɛ́p.pɤ̂n/}}
|
|-
| bank
| {{lang|th|แบงก์}}
| {{IPA|/bɛ́ŋ/}}
| means 'bank' or 'banknote'
|-
| bill
| {{lang|th|บิล}}
| {{IPA|/bīn/}} or {{IPA|/bīw/}}
|
|-
| cake
| {{lang|th|เค้ก}}
| {{IPA|/kʰéːk/}}
|
|-
| captain
| {{lang|th|กัปตัน}}
| {{IPA|/kàp.tān/}}
|
|-
| cartoon
| {{lang|th|การ์ตูน}}
| {{IPA|/kāː.tūːn/}}
|
|-
| clinic
| {{lang|th|คลินิก}}
| {{IPA|/kʰlíʔ.nìk/}}
|
|-
| computer
| {{lang|th|คอมพิวเตอร์}}
| {{IPA|/kʰɔ̄m.pʰíw.tɤ̂ː/}}
| colloquially shortened to {{lang|th|คอม}} {{IPA|/kʰɔ̄m/}}
|-
| corruption
| {{lang|th|คอร์รัปชัน}}
| {{IPA|/kʰɔ̄ː.ráp.tɕʰân/}}
|
|-
| countdown
| {{lang|th|เคานต์ดาวน์}}
| {{IPA|/kʰáw.dāːw/}}
|
|-
| dinosaur
| {{lang|th|ไดโนเสาร์}}
| {{IPA|/dāj.nōː.sǎw/}}
|
|-
| duel
| {{lang|th|ดวล}}
| {{IPA|/dūan/}}
|
|-
| e-mail
| {{lang|th|อีเมล}}
| {{IPA|/ʔīː mēːw/}}
|
|-
| fashion
| {{lang|th|แฟชั่น}}
| {{IPA|/fɛ̄ː.tɕʰân/}}
|
|-
| golf
| {{lang|th|กอล์ฟ}}
| {{IPA|/kɔ́p/}}
|
|-
| shampoo
| {{lang|th|แชมพู}}
| {{IPA|/tɕʰɛ̄m.pʰūː/}}
|
|-
| slip
| {{lang|th|สลิป}}
| {{IPA|/sàʔ.líp/}}
|
|-
| taxi
| {{lang|th|แท็กซี่}}
| {{IPA|/tʰɛ́k.sîː/}}
|
|-
| technology
| {{lang|th|เทคโนโลยี}}
| {{IPA|/tʰék.nōː.lōː.jīː, -jîː/}}
|
|-
| valve
| {{lang|th|วาล์ว}}
| {{IPA|/wāːw/}}
|
|-
| visa
| {{lang|th|วีซ่า}}
| {{IPA|/wīː.sâː/}}
|
|-
| wreath
| {{lang|th|(พวง)หรีด}}
| {{IPA|/rìːt/}}
|
|}

=== French-origin ===
{| class="wikitable"
|-
! French words !! Thai rendition !! IPA !! English translation
|-
| {{wikt-lang|fr|buffet}}
| {{lang|th|บุฟเฟต์}}
| {{IPA|/búp.fêː/}}
|
|-
| rowspan="2" | {{wikt-lang|fr|café}}
| {{lang|th|กาแฟ}}
| {{IPA|/kāː.fɛ̄ː/}}
| coffee
|-
| {{wikt-lang|th|คาเฟ่}}
| {{IPA|/kʰāː.fêː/}}
| coffee shop, restaurant serving alcoholic drinks and providing entertainment (dated)
|-
| {{wikt-lang|fr|caféine}}
| {{lang|th|กาเฟอีน}}
| {{IPA|/kāː.fēː.ʔīːn/}}
| caffeine
|-
| {{wikt-lang|fr|chauffeur}}
| {{lang|th|โชเฟอร์}}
| {{IPA|/tɕʰōː.fɤ̂ː/}}
|
|-
| {{wikt-lang|fr|consul}}
| {{lang|th|กงสุล}}
| {{IPA|/kōŋ.sǔn/}}
|
|-
| {{wikt-lang|fr|coupon}}
| {{lang|th|คูปอง}}
| {{IPA|/kʰūː.pɔ̄ŋ/}}
|
|-
| {{wikt-lang|fr|croissant}}
| {{lang|th|ครัวซ็อง}}
| {{IPA|/kʰrūa.sɔ̄ŋ/}}
|
|-
| {{wikt-lang|fr|gramme}}
| {{lang|th|กรัม}}
| {{IPA|/krām/}}
|
|-
| {{wikt-lang|fr|litre}}
| {{lang|th|ลิตร}}
| {{IPA|/lít/}}
|
|-
| {{wikt-lang|fr|mètre}}
| {{lang|th|เมตร}}
| {{IPA|/méːt/}}
| metre
|-
| {{wikt-lang|fr|parquet}}
| {{lang|th|ปาร์เกต์}}
| {{IPA|/pāː.kêː/}}
|
|-
| {{wikt-lang|fr|pétanque}}
| {{lang|th|เปตอง}}
| {{IPA|/pēː.tɔ̄ːŋ/}}
|
|}

=== Japanese-origin ===
{| class="wikitable"
|-
! Japanese words !! Thai rendition !! IPA !! Gloss
|-
| {{wikt-lang|ja|カラオケ}} ({{IPA|[kaɾaoke]}})
| {{lang|th|คาราโอเกะ}}
| {{IPA|/kʰāː.rāː.ʔōː.kèʔ/}}
| karaoke
|-
| {{wikt-lang|ja|忍者}} ({{IPA|[ɲiꜜɲd͡ʑa]}})
| {{lang|th|นินจา}}
| {{IPA|/nīn.tɕāː/}}
| ninja
|-
| {{wikt-lang|ja|寿司}} ({{IPA|[sɯɕiꜜ]}})
| {{lang|th|ซูชิ}}
| {{IPA|/sūː.tɕʰíʔ/}}
| sushi
|}

=== Khmer-origin ===
From [[Old Khmer]]
{| class="wikitable"
|-
! Khmer words !! Thai rendition !! IPA !! Gloss
|-
| {{lang|okz-Khmr|ក្រុង}} (/kroŋ/)
| {{lang|th|กรุง}}
| {{IPA|/krūŋ/}}
| capital city
|-
| {{lang|okz-Khmr|ខ្ទើយ}} (/kʰtəːj/)
| {{lang|th|กะเทย}}
| {{IPA|/kàʔ.tʰɤ̄ːj/}}
| [[kathoey]]
|-
| {{lang|okz-Khmr|ខ្មួយ}} (/kʰmuəj/)
| {{lang|th|ขโมย}}
| {{IPA|/kʰàʔ.mōːj/}}
| to steal, thief
|-
| {{lang|okz-Khmr|ច្រមុះ}} (/crɑː.moh/)
| {{lang|th|จมูก}}
| {{IPA|/tɕàʔ.mùːk/}}
| nose
|-
| {{lang|okz-Khmr|ច្រើន}} (/craən/)
| {{lang|th|เจริญ}}
| {{IPA|/tɕàʔ.rɤ̄ːn/}}
| prosperous
|-
| {{lang|okz-Khmr|ឆ្លាត}} or {{lang|okz-Khmr|ឆ្លាស}}<br />(/cʰlaːt/ or /cʰlaːh/)
| {{lang|th|ฉลาด}}
| {{IPA|/tɕʰàʔ.làːt/}}
| smart
|-
| {{lang|okz-Khmr|ថ្នល់}} (/tʰnɑl/)
| {{lang|th|ถนน}}
| {{IPA|/tʰàʔ.nǒn/}}
| road
|-
| {{lang|okz-Khmr|ភ្លើង}} (/pʰləːŋ/)
| {{lang|th|เพลิง}}
| {{IPA|/pʰlɤ̄ːŋ/}}
| fire
|-
| {{lang|okz-Khmr|ទន្លេ}} (/tɔn.leː/)
| {{lang|th|ทะเล}}
| {{IPA|/tʰáʔ.lēː/}}
| sea
|}

=== Malay-origin ===
{| class="wikitable"
|-
! Malay words !! Thai rendition !! IPA !! Gloss
|-
| {{wikt-lang|ms|kelasi}}
| {{lang|th|กะลาสี}}
| {{IPA|/kàʔ.lāː.sǐː/}}
| sailor, seaman
|-
| {{wikt-lang|ms|sagu}}
| {{lang|th|สาคู}}
| {{IPA|/sǎː.kʰūː/}}
| [[sago]]
|-
| {{wikt-lang|ms|surau}}
| {{lang|th|สุเหร่า}}
| {{IPA|/sùʔ.ràw/}}
| small mosque
|}

=== Persian-origin ===
{| class="wikitable"
|-
! Persian words !! Thai rendition !! IPA !! Gloss
|-
| {{wikt-lang|fa|گلاب‎}} ({{lang|fa-Latn|golâb}})
| {{lang|th|กุหลาบ}}
| {{IPA|/kùʔ.làːp/}}
| [[rose]]
|-
| {{wikt-lang|fa|کمربند‎}} ({{lang|fa-Latn|kamarband}})
| {{lang|th|ขาวม้า}}
| {{IPA|/kʰǎːw máː/}}
| loincloth
|-
| {{wikt-lang|fa|ترازو}} ({{lang|fa-Latn|tarâzu}})
| {{lang|th|ตราชู}}
| {{IPA|/trāː tɕʰūː/}}
| [[weighing scale|balance scale]]
|-
| {{wikt-lang|fa|سقرلات}} ({{lang|fa-Latn|saqerlât}})
| {{lang|th|สักหลาด}}
| {{IPA|/sàk.kàʔ.làːt/}}
| [[felt]]
|-
| {{wikt-lang|fa|آلت}} ({{lang|fa-Latn|âlat}})
| {{lang|th|อะไหล่}}
| {{IPA|/ʔàʔ.làj/}}
| spare part
|}

=== Portuguese-origin ===
The Portuguese were the first Western nation to arrive in what is modern-day Thailand in the 16th century during the [[Ayutthaya Kingdom|Ayutthaya period]]. Their influence in trade, especially weaponry, allowed them to establish a community just outside the capital and practise their faith, as well as exposing and converting the locals to [[Christianity]]. Thus, Portuguese words involving trade and religion were introduced and used by the locals.
{| class="wikitable"
|-
! Portuguese words !! Thai rendition !! IPA !! Gloss
|-
| {{wikt-lang|pt|carta}} / {{wikt-lang|pt|cartaz}}
| {{lang|th|กระดาษ}}
| {{IPA|/kràʔ.dàːt/}}
| paper
|-
| {{wikt-lang|pt|garça}}
| {{lang|th|(นก)กระสา}}
| {{IPA|/kràʔ.sǎː/}}
| [[heron]]
|-
| {{wikt-lang|pt|leilão}}
| {{lang|th|เลหลัง}}
| {{IPA|/lēː.lǎŋ/}}
| auction, low-priced
|-
| {{wikt-lang|pt|padre}}
| {{lang|th|บาท(หลวง)}}
| {{IPA|/bàːt.lǔaŋ/}}
| (Christian) priest<ref>{{cite web |url=http://siamportuguesestudy.blogspot.com/2010/06/blog-post_05.html |script-title=th:สยาม-โปรตุเกสศึกษา: คำเรียก "ชา กาแฟ" ใครลอกใคร ไทย หรือ โปรตุเกส |title=S̄yām-portukes̄ ṣ̄ụks̄ʹā: Khả reīyk "chā kāfæ" khır lxk khır thịy h̄rụ̄x portukes̄ |year=2010|trans-title=Siam-Portuguese Studies: The term 'tea, coffee'. Who copied someone, Thai or Portuguese? }}</ref>
|-
| {{wikt-lang|pt|pão}}
| {{lang|th|(ขนม)ปัง}}
| {{IPA|/pāŋ/}}
| bread
|-
| {{wikt-lang|pt|real}}
| {{lang|th|เหรียญ}}
| {{IPA|/rǐan/}}
| coin
|-
| {{wikt-lang|pt|sabão}}
| {{lang|th|สบู่}}
| {{IPA|/sàʔ.bùː/}}
| soap
|}

=== Tamil-origin ===
{| class="wikitable"
|-
! Tamil words !! Thai rendition !! IPA !! Gloss
|-
| {{wikt-lang|ta|கறி‎}} ({{lang|ta-Latn|kaṟi}})
| {{lang|th|กะหรี่}}
| {{IPA|/kàʔ.rìː/}}
| curry, curry powder
|-
| {{wikt-lang|ta|கிராம்பு‎}} ({{lang|ta-Latn|kirāmpu}})
| {{lang|th|กานพลู}}
| {{IPA|/kāːn.pʰlūː/}}
| [[clove]]
|-
| {{wikt-lang|ta|நெய்}} ({{lang|ta-Latn|ney}})
| {{lang|th|เนย}}
| {{IPA|/nɤ̄ːj/}}
| butter
|}

== Writing system ==
{{Main|Thai script|Thai braille}}
[[File:Kingdom of Thailand.svg|thumb|"Kingdom of Thailand" in Thai script.]]
Thai is written in the [[Thai script]], an [[abugida]] written from left to right. The language and its script are closely related to the [[Lao language]] and [[Lao script|script]]. Most literate Lao are able to read and understand Thai, as more than half of the Thai vocabulary, grammar, intonation, vowels and so forth are common with the Lao language.

The Thais adopted and modified the Khmer script to create their own writing system. While in Thai the pronunciation can largely be inferred from the script, the orthography is complex, with silent letters to preserve original spellings and many letters representing the same sound. While the oldest known inscription in the [[Khmer language]] dates from 611 CE, inscriptions in Thai writing began to appear around 1292 CE. Notable features include:

#It is an [[abugida]] script, in which the [[implicit vowel]] is a short {{IPA|/a/}} in a syllable without final [[consonant]] and a short {{IPA|/o/}} in a syllable with final consonant.
#Tone markers, if present, are placed above the final [[Syllable onset#Onset|onset]] consonant of the syllable.
#[[Vowel]]s sounding after an initial consonant can be located before, after, above or below the consonant, or in a combination of these positions.

=== Transcription ===
{{Main|Romanization of Thai}}
There is no universally applied method for transcribing Thai into the Latin alphabet. For example, the name of the main airport is transcribed variably as Suvarnabhumi, Suwannaphum, or Suwunnapoom. Guide books, textbooks and dictionaries follow different systems. For this reason, many language courses recommend that learners master the Thai script.<ref>{{cite book |last1=Pronk |first1=Marco |title=The Essential Thai Language Companion: Reference Book: Basics, Structures, Rules |date=2013 |publisher=Schwabe AG |isbn=978-3-9523664-9-3 |page=v |url=https://books.google.com/books?id=ctZBDwAAQBAJ&pg=PR5 |language=en |quote=learn the Thai alphabet as early as possible, and get rid of romanized transcriptions as soon as you can}}</ref><ref>{{cite book |last1=Juyaso |first1=Arthit |title=Read Thai in 10 Days |date=2015 |publisher=Bingo-Lingo |page=xii |url=https://books.google.com/books?id=r6dcEAAAQBAJ&pg=PR12 |language=en |quote=There have been attempts by Thai language schools to create a perfect phonetic system for learners, but none have been successful so far. ... Only Thai script is prevalent and consistent in Thailand.}}</ref><ref>{{cite book |last1=Waites |first1=Dan |title=CultureShock! Bangkok |date=2014 |publisher=Marshall Cavendish |isbn=978-981-4516-93-8 |chapter-url=https://books.google.com/books?id=gh0dAwAAQBAJ&pg=PT186 |language=en |chapter=Learning the Language: To Write or Not to Write |quote=you're far better off learning the Thai alphabet}}</ref><ref>{{cite book |last1=Cooper |first1=Robert |title=CultureShock! Thailand: A Survival Guide to Customs and Etiquette |date=2019 |publisher=Marshall Cavendish |isbn=978-981-4841-39-9 |chapter-url=https://books.google.com/books?id=o7SaDwAAQBAJ&pg=PT209 |language=en |chapter=Learning Thai: Writing Thai in English |quote=take a bit of time to learn the letters. The time you spend is saved many times over when you begin to really learn Thai.}}</ref>

Official standards are the [[Royal Thai General System of Transcription]] (RTGS), published by the [[Royal Institute of Thailand]],<ref>[http://www.royin.go.th/ Royal Thai General System of Transcription], published by the Thai Royal Institute only in Thai</ref> and the almost identical {{nowrap|[[ISO 11940-2]]}} defined by the [[International Organization for Standardization]]. The RTGS system is increasingly used in Thailand by central and local governments, especially for road signs.<ref>{{citation|url=http://www.ooh5.go.th/book/CA/CA01.pdf |archive-url=https://web.archive.org/web/20171115222340/http://www.ooh5.go.th/book/CA/CA01.pdf |archive-date=2017-11-15 |url-status=live|at=Appendix ง|language=th|title=Handbook and standard for traffic signs}}</ref> Its main drawback is that it does not indicate tone or vowel length. As the system is based on pronunciation, not orthography, reconstruction of Thai spelling from RTGS romanisation is not possible.

=== Transliteration ===
{{Main|Thai transliteration}}

The [[International Organization for Standardization|ISO]] published an international standard for the [[Thai transliteration|transliteration of Thai]] into Roman script in September 2005 ([[ISO 11940]]).<ref>[http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=29544 ISO 11940 Standard].</ref> By adding diacritics to the Latin letters it makes the transcription reversible, making it a true [[transliteration]]. Notably, this system is used by [[Google Translate]], although it does not seem to appear in many other contexts, such as textbooks and other instructional media.

== See also ==
* [[Thai script]]
* [[Thai honorifics]]
* [[Thai literature]]
* [[Thai numerals]]
* [[Thai and Lao Braille|Thai braille]]
* [[Thai typography]]
* [[Comparison of Lao and Thai]]

== Explanatory notes ==
{{Notelist}}

== References ==
=== Citations ===
{{Reflist}}

=== General and cited sources ===
{{refbegin}}
* {{lang|th|อภิลักษณ์  ธรรมทวีธิกุล และ กัลยารัตน์  ฐิติกานต์นารา.}} 2549. ''{{lang|th|การเน้นพยางค์กับทำนองเสียงภาษาไทย}}'' (''Stress and Intonation in Thai'') {{lang|th|วารสารภาษาและภาษาศาสตร์ ปีที่ 24 ฉบับที่ 2 (มกราคม&nbsp;– มิถุนายน 2549) หน้า 59–76.}} {{ISSN|0857-1406}}.
* {{lang|th|สัทวิทยา : การวิเคราะห์ระบบเสียงในภาษา. 2547. กรุงเทพฯ : สำนักพิมพ์มหาวิทยาลัยเกษตรศาสตร์.}} {{ISBN|974-537-499-7}}.
* Diller, Anthony van Nostrand, et al. 2008. ''The Tai–Kadai Languages.'' {{ISBN|978-070-071-457-5}}.
* Gandour, Jack, Tumtavitikul, Apiluck and Satthamnuwong, Nakarin. 1999. ''Effects of Speaking Rate on the Thai Tones.'' Phonetica 56, pp.&nbsp;123–134.
* [[Li Fang-Kuei|Li, Fang-Kuei]]. ''A handbook of comparative Tai''. Honolulu: University Press of Hawaii, 1977. Print.
* Rischel, Jørgen. 1998. 'Structural and Functional Aspects of Tone Split in Thai'. In ''Sound structure in language'', 2009.
* Tumtavitikul, Apiluck, 1998. ''The Metrical Structure of Thai in a Non-Linear Perspective''. Papers presented to the Fourth Annual Meeting of the Southeast Asian Linguistics Society 1994, pp.&nbsp;53–71. Udom Warotamasikkhadit and Thanyarat Panakul, eds. Temple, Arizona: Program for Southeast Asian Studies, Arizona State University.
* Apiluck Tumtavitikul. 1997. ''The Reflection on the X′ category in Thai''. ''[[Mon-Khmer Studies]]'' XXVII, pp.&nbsp;307–316.
* {{lang|th|อภิลักษณ์ ธรรมทวีธิกุล}}. 2539. ''{{lang|th|ข้อคิดเกี่ยวกับหน่วยวากยสัมพันธ์ในภาษาไทย}}'' วารสารมนุษยศาสตร์วิชาการ. 4.57–66. {{ISSN|0859-3485}} {{eISSN|2673-0502}}.
* Tumtavitikul, Appi. 1995. ''Tonal Movements in Thai''. The Proceedings of the XIIIth International Congress of Phonetic Sciences, Vol. I, pp.&nbsp;188–121. Stockholm: Royal Institute of Technology and Stockholm University.
* Tumtavitikul, Apiluck. 1994. ''Thai Contour Tones''. Current Issues in Sino-Tibetan Linguistics, pp.&nbsp;869–875. Hajime Kitamura ''et al.'', eds, Ozaka: The Organization Committee of the 26th Sino-Tibetan Languages and Linguistics, National Museum of Ethnology.
* Tumtavitikul, Apiluck. 1993. ''FO&nbsp;– Induced VOT Variants in Thai''. Journal of Languages and Linguistics, 12.1.34&nbsp;– 56.
* Tumtavitikul, Apiluck. 1993. ''Perhaps, the Tones are in the Consonants?'' ''[[Mon-Khmer Studies]]'' XXIII, pp.&nbsp;11–41.
* Higbie, James and Thinsan, Snea. ''Thai Reference Grammar: The Structure of Spoken Thai''. Bangkok: Orchid Press, 2003. {{ISBN|974-8304-96-5}}.
* Nacaskul, Karnchana ({{lang|th|ศาสตราจารย์กิตติคุณ ดร.กาญจนา นาคสกุล}}) ''Thai Phonology'', 4th printing. ({{lang|th|ระบบเสียงภาษาไทย, พิมพ์ครั้งที่ 4}}) Bangkok: Chulalongkorn Press, 1998. {{ISBN|978-974-639-375-1}}.
* Nanthana Ronnakiat ({{lang|th|ดร.นันทนา รณเกียรติ}}) ''Phonetics in Principle and Practical''. ({{lang|th|สัทศาสตร์ภาคทฤษฎีและภาคปฏิบัติ}}) Bangkok: Thammasat University, 2005. {{ISBN|974-571-929-3}}.
* Segaller, Denis. ''Thai Without Tears: A Guide to Simple Thai Speaking''. Bangkok: BMD Book Mags, 1999. {{ISBN|974-87115-2-8}}.
* [[David A. Smyth|Smyth, David]] (2002). [https://web.archive.org/web/20141129015343/https://www.uta.edu/faculty/cmfitz/swnal/projects/CoLang/courses/Ped_Grammar/thai_grammar.pdf ''Thai: An Essential Grammar''], first edition. London: Routledge.
* [[David A. Smyth|Smyth, David]] (2014). ''Thai: An Essential Grammar'', second edition. London: Routledge. {{ISBN|978-041-551-034-9}}.
* {{Citation
|last1=Tingsabadh
|first1=M.R. Kalaya
|last2=Abramson
|first2=Arthur
|year=1993
|title=Thai
|journal=Journal of the International Phonetic Association
|volume=23
|issue=1
|pages=24–28
|doi=10.1017/S0025100300004746
|s2cid=249403146
}}
{{refend}}

== Further reading ==
* Inglis, Douglas. 1999. [https://www.academia.edu/7152881/Lexical_conceptual_structure_of_numeral_classifiers_in_Thai-Part_1 Lexical conceptual structure of numeral classifiers in Thai-Part 1]. Payap Research and Development Institute and The Summer Institute of Linguistics. Payap University.
* Inglis, Douglas. 2000. [https://www.academia.edu/7152883/Grammatical_conceptual_structure_of_numeral_classifiers_in_Thai-Part_2 Grammatical conceptual structure of numeral classifiers in Thai-Part 2]. Payap Research and Development Institute and The Summer Institute of Linguistics. Payap University.
* Inglis, Douglas. 2003. Conceptual structure of numeral classifiers in Thai. In Eugene E. Casad and Gary B. Palmer (eds.). Cognitive linguistics and non-Indo-European languages. CLR Series 18. De Gruyter Mouton. 223–246. {{ISBN|978-311-017-371-0}}

== External links ==

{{InterWiki|code=th}}
{{Wikiquote|Thai proverbs}}
{{Wikivoyage|Thai phrasebook|Thai|a phrasebook}}
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* [http://www.phon.ucl.ac.uk/home/sampa/thai.htm IPA and SAMPA for Thai]
* [http://hdl.handle.net/10106/6079 Consonant Ear Training Tape]
* [http://hdl.handle.net/10106/9760 Tones of Tai Dialect]



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{{Tai-Kadai languages}}
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