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
• unsupported
• irrational
• invalid
• false
• unreasoned
• unnecessary
• absurd
• misleading
• illogical
• foundationless
• fallacious
• nonvalid
• inconsistent
• weak
• implausible
• specious
• wrong
• untenable
• unconscionable
• misled
• unconvincing
• meaningless
• unsound
• gratuitous
• flimsy
• stupid
• uncalled-for
• foolish
• nonsensical
• asinine
• nonlogical
• silly
• fatuous
• preposterous
• insane
• unwise
• ill-advised
• simpleminded
• mad
• 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

An initial report that the incident involved a vehicle collision was later determined to be unfounded, according to the Sheriff’s Office. — Sacbee.com, 17 Aug. 2026

Nonetheless, emphasizing unfounded truths in various frantic phrases won’t gain followers to your point of view. — Sun Sentinel Editorial Board, Sun Sentinel, 15 Aug. 2026

Experts say these concerns are largely unfounded, but the conversation is bringing to light misconceptions about testosterone and masculinity. — Sara Moniuszko, USA Today, 13 Aug. 2026

If video can’t be located and there is no ballistic evidence found at the scene — and there are no reliable witnesses — the job gets marked unfounded. — Rocco Parascandola, New York Daily News, 13 Aug. 2026