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

"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 rumors frequently fly in those situations, and a vital part of an anchor’s job is not giving them oxygen.

From Seattle Times • Jul. 9, 2021

Unfounded rumor of conspiracy of Spaniards to murder Americans.

From The Shirley Letters from California Mines in 1851-52 by Clappe, Louise Amelia Knapp Smith

Vocabulary lists containing unfounded

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

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

100 SAT Words Beginning with "U"

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

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

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!