- (n.) Not well; feeble; infirm; sickly; as, he had an invalid daughter.
- (v.t.) To make or render invalid or infirm.
- (a.) Of no force, weight or cogency; not valid; weak.
- (a.) Having no force, effect or efficacy; void; null; as, an invalid contract or agreement.
- (v.t.) To classify or enroll as an invalid.
- (a.) A person who is weak and infirm; one who is disabled for active service; especially, one in chronic ill health.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). invalid. Retrieved September 22, 2026, from http://smartdefine.org/invalid/definitions/2023372 |
| Chicago | Webster's. 2011. "invalid" http://smartdefine.org/invalid/definitions/2023372 (accessed September 22, 2026). |
| Harvard | Webster's 2011, invalid, Smart Define, viewed 22 September, 2026, <http://smartdefine.org/invalid/definitions/2023372>. |
| MLA | Webster's. "invalid" 27 May 2011. Web. 22 September 2026. <http://smartdefine.org/invalid/definitions/2023372> |