W18

W18 may refer to:

• W-18 (drug), a designer drug
• British NVC community W18, a woodland community in the British National Vegetation Classification system
• Hansa-Brandenburg W.18, a German flying boat fighter
• , a tug of the Royal Navy
• Malgana language
• Mercedes-Benz W18, an automobile
• Snub dodecahedron
• Suburban Airport, in Anne Arundel County, Maryland, United States
• W18 engine, an eighteen-cylinder engine
• Water-jugs-in-stand (hieroglyph), an Egyptian hieroglyph