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

The victim of his sacrifice is Gretchen, a virgin whom Faust seduces and abandons in his devilish reverie, and who kills their illegitimate child. —Merve Emre, New Yorker, 1 Dec. 2025

Trump has accused Maduro of being an illegitimate president after an election that most independent observers believe was stolen. —Richard Hall, Time, 29 Nov. 2025

Based in Venezuela, the Cartel de los Soles is headed by Nicolás Maduro and other high-ranking individuals of the illegitimate Maduro regime who have corrupted Venezuela's military, intelligence, legislature, and judiciary. —Simon Crerar, MSNBC Newsweek, 25 Nov. 2025

But illegitimate examples had thinner insulators or none at all, and little or no safety tape. —Andrew Moseman, IEEE Spectrum, 22 Nov. 2025

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