invalid

2
[in-val-id]
adjective
  1. not valid; without force or foundation; indefensible.
  2. deficient in substance or cogency; weak.
  3. void or without legal force, as a contract.

Origin of invalid

2
1625–35; < Medieval Latin invalidus, Latin: weak; see invalid1
Related formsin·val·id·ly, adverbin·val·id·ness, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for invalidly

invalid

1
noun
    1. a person suffering from disablement or chronic ill health
    2. (as modifier)an invalid chair
adjective
  1. suffering from or disabled by injury, sickness, etc
verb (tr)
  1. to cause to become an invalid; disable
  2. (usually foll by out; often passive) mainly British to require (a member of the armed forces) to retire from active service through wounds or illness
Derived Formsinvalidity, noun

Word Origin for invalid

C17: from Latin invalidus infirm, from in- 1 + validus strong

usage

It is best to avoid using the term invalid when referring to people with chronic illnesses or disabilities

invalid

2
adjective
  1. not valid; having no cogency or legal force
  2. logic (of an argument) having a conclusion that does not follow from the premises: it may be false when the premises are all true; not valid
Derived Formsinvalidity (ˌɪnvəˈlɪdɪtɪ) or invalidness, nouninvalidly, adverb

Word Origin for invalid

C16: from Medieval Latin invalidus without legal force; see invalid 1
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for invalidly

invalid

adj.1

"not strong, infirm," 1640s, from Latin invalidus "not strong, infirm, weak, feeble," from in- "not" (see in- (1)) + validus "strong" (see valid). Specific meaning "infirm from sickness, disease, or injury" is from 1640s.

invalid

n.

1709, originally of disabled military men, from invalid (adj.1). Invalides is short for French Hôtel des Invalides, home for old and disabled soldiers in the 7th arrondissement of Paris.

invalid

adj.2

"of no legal force," 1630s, from special use of Latin invalidus (see invalid (adj.1)).

Online Etymology Dictionary, © 2010 Douglas Harper

invalidly in Medicine

invalid

[ĭnvə-lĭd]
n.
  1. One who is incapacitated by a chronic illness or disability.
adj.
  1. Incapacitated by illness or injury.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.