illegitimate
Americanadjective
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born of parents who are not married to each other; born out of wedlock.
an illegitimate child.
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not legitimate; not sanctioned by law or custom.
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unlawful; illegal.
an illegitimate action.
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irregular; not in good usage.
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Logic. not in accordance with the principles of valid inference.
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Obsolete. (formerly, in London)
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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.
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acting in or producing such productions.
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noun
verb (used with object)
adjective
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born of parents who were not married to each other at the time of birth; bastard
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forbidden by law; illegal; unlawful
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contrary to logic; incorrectly reasoned
noun
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
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
One of the protesters, Hussein Mohammed al-Yafai, told AFP he had come out to "reject the illegitimate measures taken by Saudi Arabia... against the South."
From Barron's • Jan. 17, 2026
Though it’s etymologically illegitimate, octopi is now so common that dictionaries list it as a second choice after octopuses.
From "Woe Is I" by Patricia T. O'Conner
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
