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 board investigated 69 allegations in the complaints, finding that 13 were sustained, 14 were unsustained, 34 were unfounded, seven were exonerated and one where no finding was issued, according to the report. — Chase Hunter, Mercury News, 24 July 2026

Such complaints are more than an unfounded nostalgia for a bygone age. — Austin Sarat, The Conversation, 23 July 2026

Historically, fears surrounding novels, radio, and television proved largely unfounded, though each gradually reshaped human habits. — Michael Edmondson, Forbes.com, 21 July 2026

Tincon last spring said the concerns were unfounded and described itself as a responsible corporate neighbor, but ended up withdrawing its application before a vote. — Don Stacom, Hartford Courant, 18 July 2026