invalid
1 Americannoun
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an infirm or sickly person.
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a person who is too sick or weak to take care of their own needs.
My father was an invalid the last ten years of his life.
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Archaic. a member of the armed forces disabled for active service.
adjective
-
unable to care for oneself due to infirmity or disability.
his invalid sister.
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of or for invalids.
invalid diets.
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(of things) in poor or weakened condition.
the invalid state of his rocking chair.
verb (used with object)
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to affect with disease; make an invalid.
He was invalided for life.
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to remove from or classify as not able to perform active service, as an invalid.
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British. to remove or evacuate (military personnel) from an active theater of operations because of injury or illness.
verb (used without object)
adjective
-
not valid; not founded in truth, fact, or logic, and hence weak and indefensible; unsound; untenable.
The entire argument depends on an invalid assumption.
- Synonyms:
- incorrect, inaccurate, false, erroneous, unsubstantiated, unfounded, groundless, baseless
-
deficient in effectiveness; inadequate.
Self-perception is an invalid method of judging one's own biases.
-
void or without legal force, as a contract.
Without the grandfather clause, thousands of such warranties would now be invalid. The coupon is invalid in our state.
- Synonyms:
- null and void
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not accepted or permitted because a required element or the necessary form is lacking; not usable.
Anything with fewer than five characters is an invalid password, and you’ll get an error message prompting you to pick something more secure.
noun
adjective
verb
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to cause to become an invalid; disable
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(usually foll by out; often passive) to require (a member of the armed forces) to retire from active service through wounds or illness
adjective
-
not valid; having no cogency or legal force
-
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
Usage
It is best to avoid using the term invalid when referring to people with chronic illnesses or disabilities
Other Word Forms
Derived Forms
Conjugated Forms
Present
-
has invalidedperfect 3rd person singular
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have invalidedperfect
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has been invalidingperfect progressive 3rd person singular
-
have been invalidingperfect progressive
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is invalidingprogressive 3rd person singular
-
are invalidingprogressive
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invalidssingular 3rd person
-
invalidingparticiple
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am invalidingprogressive 1st person singular
Past
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had invalidedperfect
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were invalidingprogressive plural
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invalidedsimple
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invalidedparticiple
-
had been invalidingperfect progressive
-
was invalidingprogressive singular
Future
Etymology
Origin of invalid1
First recorded in 1635–45; from French invalide, from Latin invalidus “weak, feeble, infirm”; See in- 3, valid
Origin of invalid2
First recorded in 1630–40; from Latin invalidus “weak, feeble”; see invalid 1
Explanation
A person who is very sick or injured and needs frequent care is an invalid. Also, something no longer current or useful is invalid. The main uses of this word have to do with people and things that don't work very well anymore. A driver's license that has expired is invalid — it needs to be renewed. If you lost your health insurance, it's invalid. People who are called invalids are disabled or incapacitated severely. Be careful with this word, because some think it is inappropriate, since it sounds as if some people are not as valid as others based on physical capability.
Vocabulary lists containing invalid
"Sorry, Wrong Number," Vocabulary from the play
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"Sorry, Wrong Number," Vocabulary from the play
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The Suffix -id, Part 1
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The basic problem, as these courts identified, is that the government failed to accuse these doctors of any plausibly unlawful conduct, rendering the subpoenas invalid.
From Slate • May 19, 2026
The town government last month said that a resignation request submitted by family members would be invalid, the Japan Times added.
From BBC • May 9, 2026
"It is declared that the vote of the National Assembly taken on 13 December 2022... is inconsistent with the Constitution, invalid, and it is set aside," the Constitutional Court's Chief Justice Mandisa Maya said.
From Barron's • May 8, 2026
However, she had written an F down as part of her number plate instead of an S, rendering the insurance technically invalid.
From BBC • Apr. 20, 2026
This was owing largely to the eleven years she had spent caring for her invalid mother, which had left her with some proficiency as a nurse and an inability to face strong sunlight without blinking.
From "The Haunting of Hill House" by Shirley Jackson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
