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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.

Having overturned a 2-0 deficit to stun Manchester City at the same stage last season, that confidence is not unfounded.

From BBC • Apr. 1, 2026

"By shedding light on the biology and ecology of the great white shark, research can help replace unfounded myths with genuine understanding."

From Science Daily • Mar. 11, 2026

Some criticisms of the accelerated approval pathway aren’t unfounded.

From The Wall Street Journal • Mar. 3, 2026

Guatemala's Public Prosecutor's Office called the accusations "baseless, factually unfounded and completely malicious."

From Barron's • Feb. 17, 2026

In conversations with faculty members I began to worry the issue, only to be told that my unease was unfounded.

From "Hunger of Memory" by Richard Rodriguez

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.