from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. One who is incapacitated by a chronic illness or disability.
  • adj. Incapacitated by illness or injury.
  • adj. Of, relating to, or intended for invalids.
  • transitive v. To incapacitate physically.
  • transitive v. Chiefly British To release or exempt from duty because of ill health: "I was not quite sick enough to be invalided out, even though I was of no more use” ( Mary Lee Settle).
  • adj. Not legally or factually valid; null: an invalid license.
  • adj. Falsely based or reasoned; faulty: an invalid argument.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Not valid; not true, correct, acceptable or appropriate.
  • n. One who is confined to home or bed because of illness, disability or injury
  • n. Any person with a disability.
  • adj. Intended for use by an invalid.
  • v. To exempt from duty because of injury or ill health.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Of no force, weight, or cogency; not valid; weak.
  • adj. Having no force, effect, or efficacy; void; null.
  • adj. Not well; feeble; infirm; sickly.
  • n. 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.
  • transitive v. To make or render invalid or infirm.
  • transitive v. To classify or enroll as an invalid.

from The Century Dictionary and Cyclopedia

  • Not valid; of no force, weight, or cogency; weak.
  • In law, having no validity or binding force; wanting efficacy; null; void: as, an invalid contract or agreement.
  • Deficient in health; infirm; weak; sick.
  • n. An infirm or sickly person; one who is affected by disease or disabled by any infirmity.
  • n. Hence Something that is damaged, or the worse for wear, but not so much as to be wholly unserviceable.
  • To affect with disease; render an invalid: chiefly in the past participle.
  • To register as an invalid; enroll on the list of invalids in the military or naval service; give leave of absence from duty on account of ill health.
  • To cause one's self to be registered as an invalid.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. no longer valid
  • adj. having no cogency or legal force
  • v. force to retire, remove from active duty, as of firemen
  • v. injure permanently
  • n. someone who is incapacitated by a chronic illness or injury


from The American Heritage® Dictionary of the English Language, 4th Edition

From invalid2 (influenced by French invalide, sickly, infirm).
Latin invalidus, weak : in-, not; see in-1 + validus, strong (from valēre, to be strong; see wal- in Indo-European roots).

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Latin invalidus ("infirm, weak"), from in- ("not") + validus ("strong")


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