Invalid
Template:Sister project Invalid may refer to:
- Patient, a sick person
- one who is confined to home or bed because of illness, disability or injury (sometimes considered a politically incorrect term)
- Invalid (film), a 2023 Slovak black comedy movie
- .invalid, a top-level Internet domain not intended for real use
As the opposite of valid:
- Validity (logic), in logic, true premises cannot lead to a false conclusion
- Validity (statistics), a measure which is measuring what it is supposed to measure