Definitions

unfounded

[uhn-foun-did] / ʌnˈfaʊn dɪd /

ADJECTIVE

not based on fact

Synonyms

STRONGEST

baseless deceptive fabricated false gratuitous groundless illogical misleading spurious unjustified unproven unsubstantiated untrue untruthful unwarranted

WEAK

fallacious foundationless idle mendacious off-base trumped-up uncalled-for unreal vain without basis without foundation

Antonyms

STRONGEST

called-for correct genuine honest justified real reasonable right true truthful warranted

WEAK

founded proven substantiated supported

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.

Unfounded claims that the Artemis II mission detected a mysterious moving object on the moon's surface also racked up millions of views across platforms.

From Barron's • Apr. 11, 2026

Unfounded claims about the Kinsey Institute’s work prompted the Indiana Legislature to block the flow of state dollars to the sex research institute.

From Los Angeles Times • May 23, 2023

Unfounded claims that the gunman was an immigrant living in the U.S. illegally, or transgender, quickly emerged on Twitter, Reddit and other social media platforms.

From Seattle Times • May 25, 2022

"There was no evidence presented which supports that Sofia received a physical or emotional injury. This case is closed as Unfounded."

From Fox News • Nov. 28, 2021

"Unfounded assumptions," Buxton, in the pride of office, characterised these simple interrogatories.

From Punch, or the London Charivari, November 25, 1893 by Various

Vocabulary lists containing unfounded

Fake It 'Til You Make It: Synonyms for "False"

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100 SAT Words Beginning with "U"

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"Laws are not the only way to boost immunization”: an editorial from Nature

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