Invalid may refer to: *

Patient A patient is any recipient of health care services that are performed by healthcare professionals. The patient is most often ill or injured and in need of treatment by a physician, nurse, optometrist, dentist, veterinarian, or other health ...

, a sick person * one who is confined to home or bed because of illness,

disability Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be cognitive, developmental, intellectual, mental, physical, s ...

or injury (sometimes considered a

politically incorrect ''Political correctness'' (adjectivally: ''politically correct''; commonly abbreviated ''PC'') is a term used to describe language, policies, or measures that are intended to avoid offense or disadvantage to members of particular groups in socie ...

term) *

.invalid name invalid is reserved by the Internet Engineering Task Force (IETF) in RFC 2606 (June 1999) as a domain name that may not be installed as a top-level domain in the Domain Name System (DNS) of the Internet.RFC 2606 (BCP 32), ''Reserved Top Lev ...

, a top-level Internet domain not intended for real use As the opposite of valid: *

Validity Validity or Valid may refer to: Science/mathematics/statistics: * Validity (logic), a property of a logical argument * Scientific: ** Internal validity, the validity of causal inferences within scientific studies, usually based on experiments ...

, in logic, true premises cannot lead to a false conclusion *

Validity (statistics) Validity is the main extent to which a concept, conclusion or measurement is well-founded and likely corresponds accurately to the real world. The word "valid" is derived from the Latin validus, meaning strong. The validity of a measurement tool ( ...

, a measure which is measuring what it is supposed to measure

See also