Webster's Revised Unabridged Dictionary · 1913

Invalid

Invalid , adjective

[Prefix in- not + valid: compare French invalide, Latin invalidus infirm, weak. Compare Invalid infirm.]

1.
Of no force, weight, or cogency; not valid; weak.
2.
(Law) Having no force, effect, or efficacy; void; null; as, an invalid contract or agreement.

Invalid (?; 277) , noun

[French invalide, n. & a., Latin invalidus, a. See Invalid null.]

A person who is weak and infirm; one who is disabled for active service; especially, one in chronic ill health who is unable to care for himself.

Invalid , adjective

[See Invalid, n.]

Not well; feeble; infirm; sickly; as, he had an invalid daughter.

Invalid , transitive verb

1.
To make or render invalid or infirm.
Invalided, bent, and almost blind. — Dickens
2.
To classify or enroll as an invalid.
Peace coming, he was invalided on half pay. — Carlyle