invalid

1 of 4

adjective (1)

in·​val·​id (ˌ)in-ˈva-ləd 

: not valid:

a

: being without foundation or force in fact, truth, or law

an invalid assumption

declared the will invalid

b

: logically inconsequent

invalidly

(ˌ)in-ˈva-ləd-lē 

adverb

invalid

2 of 4

noun

in·​va·​lid ˈin-və-ləd 

 British usually  -ˌlēd

: one who is sickly or disabled

invalid

3 of 4

verb

in·​va·​lid ˈin-və-ləd 

-ˌlid,

 British usually  -ˌlēd,

 or  ˌin-və-ˈlēd

invalided; invaliding; invalids

transitive verb

1

: to remove from active duty by reason of sickness or disability

2

: to make sickly or disabled

invalid

4 of 4

adjective (2)

in·​va·​lid ˈin-və-ləd 

 British usually  -ˌlēd

1

: affected by disease or disability : sickly

2

: of, relating to, or suited to one that is sick

an invalid chair

Synonyms

Adjective (1)

• null
• void

Adjective (2)

• fragile
• weak
• weakly
• sickly
• dying
• sick
• frail
• ailing
• feeble

Examples of invalid in a Sentence

Adjective (1)

the treaty is invalid once one side violates it

that's an invalid assumption on your part

an argument which has one untrue premise is invalid

an invalid claim that can be easily disproved by the facts

Noun

Her husband has become an invalid.

Adjective (2)

an old and now invalid woman who rarely gets out anymore

Recent Examples on the Web

Adjective

Any unofficial or decorative mark—including, of course, souvenir stamps—violates that rule and can render the document invalid. —Lauren Dana Ellman, Travel + Leisure, 25 Oct. 2025

However, the registrar of voters office said in March that the group fell 1,027 short of the number required because of signatures determined to be invalid or in need of information such as a date or an address. —Ashley MacKin Solomon, San Diego Union-Tribune, 24 Oct. 2025

Noun

By the act concerning invalids, passed in June 1794, the secretary at war is ordered to place on the pension list all persons whose names are contained in a report previously made by him to congress. —Liz Tracey, JSTOR Daily, 29 July 2025

Concern grew that the fabulous invalid, as the theater has long been dubbed, might be down for the count. —Charles McNulty, Los Angeles Times, 4 Dec. 2023

Verb

If this is ascertained, the BBC quotes an LA attorney saying this would render Hackman’s will invalid, and mean his children could have a claim to the estate. —Caroline Frost, Deadline, 16 Mar. 2025

DeSantis's office has said all options are on the table for their fight, but a legal ruling invaliding the agreement that currently gives Disney near-total control of the district would be the easiest resolution for the governor's headache. —Jack Birle, Washington Examiner, 8 Apr. 2023

Word History

Etymology

Adjective (1)

Latin invalidus weak, from in- + validus strong — more at valid

Adjective (2)

Latin & French; French invalide, from Latin invalidus

First Known Use

Adjective (1)

1542, in the meaning defined above

Noun

1701, in the meaning defined above

Verb

1787, in the meaning defined at sense 1

Adjective (2)

1642, in the meaning defined at sense 1

Kids Definition

invalid

1 of 4 adjective

in·​val·​id (ˈ)in-ˈval-əd 

: having no force or effect : not valid

an invalid parking sticker

an invalid assumption

invalidity

ˌin-və-ˈlid-ət-ē

noun

invalidly

(ˈ)in-ˈval-əd-lē 

adverb

invalid

2 of 4 adjective

in·​va·​lid ˈin-və-ləd 

1

: suffering from disease or disability : sickly

2

: of, relating to, or suited to an invalid

invalid

3 of 4 noun

like ²

 

: one who is sickly or disabled

invalid

4 of 4 verb

in·​va·​lid ˈin-və-ləd 

-ˌlid

: to make sickly or disabled

Etymology

Adjective

from earlier invalid "not having a sound basis in fact or reason, not valid," from Latin invalidus "weak"

Adjective

from French invalide "suffering from a disease, sickly," from Latin invalidus "weak"

Medical Definition

invalid

1 of 3 adjective

in·​va·​lid

ˈin-və-ləd, British usually -ˌlēd

1

: affected by disease or disability : sickly

2

: of, relating to, or suited to one that is sick

an invalid chair

invalid

2 of 3 noun

: one who is sickly or disabled

invalid

3 of 3 transitive verb

in·​va·​lid

ˈin-və-ləd, -ˌlid, British usually -ˌlēd or ˌin-və-ˈlēd

1

: to remove from active duty by reason of sickness or disability

was invalided out of the army

2

: to make sickly or disabled

a patient invalided by valvular disease

Legal Definition

invalid

adjective

in·​val·​id in-ˈva-ləd 

: being without force or effect under the law

declared the will invalid

invalidly adverb