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Synonyms

illegitimate

American  
[il-i-jit-uh-mit, il-i-jit-uh-meyt] / ˌɪl ɪˈdʒɪt ə mɪt, ˌɪl ɪˈdʒɪt əˌmeɪt /

adjective

  1. born of parents who are not married to each other; born out of wedlock.

    an illegitimate child.

  2. not legitimate; not sanctioned by law or custom.

  3. unlawful; illegal.

    an illegitimate action.

  4. irregular; not in good usage.

  5. Logic. not in accordance with the principles of valid inference.

  6. Obsolete. (formerly, in London)

    1. of or relating to stage plays in which musical numbers were inserted because of laws that gave only a few theaters the exclusive right to produce straight dramas.

    2. acting in or producing such productions.


noun

  1. a person recognized or looked upon as illegitimate.

verb (used with object)

illegitimated, illegitimating
  1. to declare illegitimate.

illegitimate British  
/ ˌɪlɪˈdʒɪtɪmɪt /

adjective

  1. born of parents who were not married to each other at the time of birth; bastard

  2. forbidden by law; illegal; unlawful

  3. contrary to logic; incorrectly reasoned

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

noun

  1. an illegitimate person; bastard

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Related Words

See illegal.

Other Word Forms

  • illegitimacy noun
  • illegitimately adverb
  • illegitimateness noun
  • illegitimation noun

Etymology

Origin of illegitimate

First recorded in 1530–40; il- 2 + legitimate

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.

If ever there was justification for an asterisk next to a record, his illegitimate assault on a scoring record is it.

From Los Angeles Times • Mar. 14, 2026

Novo officially dropped Hims in June and accused the company of “deceptive promotion and selling of illegitimate, knockoff versions of Wegovy that put patient safety at risk.”

From Barron's • Mar. 9, 2026

The company says that it is “especially concerned about the use of A.I. to help individual humans or small groups gain unprecedented and illegitimate forms of concentrated power.”

From Slate • Feb. 25, 2026

Years of decay have left oil fields, pipelines and refineries in disrepair, with investors wary of sinking large sums and signing deals with a government led by Rodríguez that is widely viewed as illegitimate.

From The Wall Street Journal • Feb. 12, 2026

Civil rights advocates argue that individual group members “represent” the race and that hierarchies of power that lack diversity are illegitimate.

From "The New Jim Crow" by Michelle Alexander