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

In 2004, a Senate Intelligence Committee report concluded the CIA had provided unfounded assessments of the threat posed by Iraq that the Bush administration had relied on to justify going to war. — Chicago Tribune, 9 July 2026

Julie confirms secret romance with Peter Weber After years of rumors, LaPlaca confirms the speculation surrounding her and Weber was not entirely unfounded. — Deirdre Durkan, PEOPLE, 7 July 2026

For decades, African football has faced criticism and skepticism, often based on unfounded racial stereotypes. — Pj Green, Kansas City Star, 2 July 2026

The early fears that Hamilton was an existential threat to the university seemed—so far, at least—unfounded. — Ann Manov, Harpers Magazine, 30 June 2026