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

Nelly herself is heavily reinterpreted by Fennell, imagined in this film as the illegitimate daughter of an aristocrat who serves as Cathy’s maid; the film also runs with modern readings of her character as a more proactive meddler in the doomed love between the main characters. —Wilson Chapman, IndieWire, 13 Feb. 2026

Advertisement Played by Vietnamese American actor Hong Chau, the Nelly of Fennell's film is reframed as the illegitimate daughter of a lord, and she is directly involved in the misunderstandings that drive the movie's central tragedies. —Megan McCluskey, Time, 13 Feb. 2026

The report also accuses each campus of hosting speakers who condoned Hamas and called Israel illegitimate without any events that were pro-Israel. —Lexi Lonas Cochran, The Hill, 12 Feb. 2026

Visit our website First is a liberal-democratic tradition that rejects illegitimate authority and domination. —Emily Chamlee-Wright, Washington Post, 6 Feb. 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