illegitimate

adjective

il·​le·​git·​i·​mate ˌi-li-ˈji-tə-mət 

1

a

: not recognized as lawful offspring

b

: born of parents not married to each other

2

a

: not sanctioned by law : illegal

an illegitimate government

… a retaliatory, harassing, or other illegitimate motive.

—Diamond "D" Const. Corp. v. McGowan, 282 F. 3d 191 (2002)

b

: not authorized by good usage

c

of a taxon : published but not in accordance with the rules of the relevant international code

3

: not reasonable or fair

were fired for illegitimate reasons

4

: not rightly deduced or inferred : illogical

5

: departing from the regular : erratic

illegitimately adverb

Synonyms of illegitimate

• spurious
• misbegotten
• supposititious
• adopted
• natural
• orphaned

Examples of illegitimate in a Sentence

She thinks that my concerns are illegitimate.

They were fired from their jobs for illegitimate reasons.

Recent Examples on the Web

In statements to ProPublica, the credit bureaus said that many complaints are illegitimate, including a large volume filed by credit repair organizations that charge customers to challenge negative information on their reports. —Joel Jacobs, CNN Money, 11 Mar. 2026

Once a sky-blue democracy is restored, may Trump’s days of infamy be ruled illegitimate and his name and legacy duly tainted by all of history, darkly blackened or cautiously reddened in the honest records that this twerp and his twisted cohorts have conspired so heinously to whitewash. —Voice Of The People, New York Daily News, 8 Mar. 2026

Even with policies such as unlimited paid time off, singles may hesitate to take vacations, fearing that their managers will see their reasons for taking time off as illegitimate. —Peter McGraw, The Conversation, 6 Mar. 2026

Crime abhors a vacuum, and in Tommy’s absence, the Peaky Blinders gang has reformed under the aegis of his sociopathic illegitimate son Duke (Barry Keoghan). —Damon Wise, Deadline, 5 Mar. 2026

Word History

First Known Use

1536, in the meaning defined at sense 1a

Rhymes for illegitimate

• legitimate

Kids Definition

illegitimate

adjective

il·​le·​git·​i·​mate ˌil-i-ˈjit-ə-mət 

1

: born of a father and mother who are not married

2

: illegal

illegitimately adverb

Legal Definition

illegitimate

adjective

il·​le·​git·​i·​mate ˌi-li-ˈji-tə-mət 

1

: not recognized by the law as offspring

specifically : born out of marriage

Note: An illegitimate child is usually legitimated by his or her parents' later marriage. Illegitimate children generally have the same inheritance rights under intestate successions as legitimate children; statutes limiting their inheritance rights have been found to violate the equal protection clause.

2

: not valid according to law

illegitimate noun