invalid

Etymology 1

in- + valid

adj

1. Not valid; not true, correct, acceptable or appropriate.
   Your argument is invalid because it uses circular reasoning.
   This invalid contract cannot be legally enforced.

Etymology 2

From Middle French invalide, from Latin invalidus (“infirm, weak”), from in- (“not”) + validus (“strong”).

noun

1. (dated, sometimes offensive) Any person with a disability or illness.
2. (dated, sometimes offensive) A person who is confined to home or bed because of illness, disability or injury; one who is too sick or weak to care for themselves.
3. (archaic) A disabled member of the armed forces; one unfit for active duty due to injury.

adj

1. Suffering from disability or illness.
   Invalidism therefore referred to a lack of power as well as a tendency toward illness. It is for this reason that I choose to discuss the invalid woman rather than just the ill one. 2000, Diane Price Herndl, Invalid Women: Figuring Feminine Illness in American Fiction and Culture, 1840-1940, University of North Carolina Press, page 1
2. Intended for use by an invalid.

verb

1. (Britain, transitive) To exempt from (often military) duty because of injury or ill health.
   He was invalided home after the car crash.
   Blackadder: Right, Baldrick, this is an old trick I picked up in the Sudan. We tell HQ that I’ve gone insane, and I’ll be invalided back to Blighty before you can say "wibble" — a poor, gormless idiot. 1989, Richard Curtis, Ben Elton, “Goodbyeee”, in Blackadder Goes Forth
   The Japanese armored cruiser Nisshin has been hit badly. Shells have sheared off several main guns and virtually disarmed the vessel. In the middle of all this, one Ensign Isoroku Yamamoto loses two fingers to the remains of an explosion. If he'd lost a third, he would've been invalided out of military service. Thus, by the retention of a single digit would there be rather large consequences a few decades later on down the line. 18 September 2019, Drachinifel, 26:33 from the start, in Battle of Tsushima - When the 2nd Pacific Squadron thought it couldn't get any worse..., archived from the original on 2022-12-04
2. (transitive) To make invalid or affect with disease.