Synonyms of unfounded

unfounded

adjective

ˌən-ˈfau̇n-dəd 

as in unreasonable

having no basis in reason or fact

the accusation proved to be unfounded

Synonyms & Similar Words

• unreasonable
• baseless
• groundless
• unsubstantiated
• unwarranted
• irrational
• unsupported
• invalid
• false
• unreasoned
• unnecessary
• absurd
• misleading
• illogical
• foundationless
• fallacious
• inconsistent
• weak
• nonvalid
• implausible
• wrong
• specious
• untenable
• misled
• unconscionable
• meaningless
• unconvincing
• unsound
• gratuitous
• stupid
• flimsy
• uncalled-for
• foolish
• nonsensical
• asinine
• silly
• nonlogical
• fatuous
• preposterous
• insane
• unwise
• ill-advised
• mad
• simpleminded
• wacky
• harebrained
• nutty
• senseless
• brainless
• crackpot
• crazy
• half-witted

Antonyms & Near Antonyms

• reasonable
• justified
• valid
• good
• hard
• reasoned
• confirmed
• just
• well-founded
• certified
• substantiated
• logical
• rational
• well-grounded
• true
• informed
• real
• validated
• actual
• wise
• sensible
• genuine
• certain
• verified
• sane
• sure
• corroborated
• sober
• clear
• plausible
• solid
• sound
• credible
• convincing
• compelling
• commonsense
• persuasive
• satisfying
• cogent

Example Sentences

Recent Examples of unfounded

The early concern that nonprofits couldn’t absorb capital at that scale turned out to be unfounded across more than a thousand organizations. — Max Simkoff, Fortune, 7 Aug. 2026

Fortunately, this fear is unfounded, and there's a clear, penalty-free way back into compliance. — Nathalie Goldstein, Forbes.com, 7 Aug. 2026

Who called off the engagement and why was the stuff of subsequent and perhaps unfounded speculation. — Armando Salguero Outkick, FOXNews.com, 7 Aug. 2026

That speculation, however, proved to be unfounded, and BeBe ultimately placed third on the season overall. — Joey Nolfi, Entertainment Weekly, 31 July 2026