dubious

1 giving good reason for being doubted, questioned, or challenged any letter bearing the signature of Geronimo would be of dubious authenticity, to say the least Synonyms debatable, disputable, dodgy [chiefly British], doubtable, doubtful, dubitable, equivocal, fishy, problematic (also problematical), queer, questionable, shady, shaky, suspect, suspiciousRelated Words alleged, so-called, supposed; moot; ambiguous, open, unclear; uncertain, undecided, undetermined; far-fetched, flimsy, improbable, unlikely, weakNear Antonyms decisive, definitive; clear, obvious, open-and-shut, positiveAntonyms certain, hands-down, incontestable, indisputable, indubitable, questionless, sure, undeniable, undoubted, unproblematic, unquestionable

2 slow to begin or proceed with a course of action because of doubts or uncertainty I'm dubious about our plan to go hang gliding without having had any training Synonyms cagey (also cagy), disinclined, hesitant, indisposed, loath (also loth or loathe), reluctant, reticentRelated Words uneager, unenthusiastic; averse, unwilling; ambivalent, conflicted, doubtful, faltering, halting, indecisive, infirm, irresolute, questioning, skeptical, uncertain, undecided, unsure, vacillating, wobbly (also wabbly); fainthearted, shy, timidNear Antonyms eager, enthusiastic, glad, happy, keen; ready, willing; certain, decided, determined, resolute, sure, unquestioningAntonyms disposed, inclined

3 not likely to be true or to occur made the dubious claim of being of royal blood Synonyms doubtful, improbable, far-fetched, flimsy, questionable, unapt, unlikelyRelated Words implausible, impossible, inconceivable, incredible, unbelievable, unimaginable, unthinkable; absurd, bizarre, crazy, fantastic (also fantastical), foolish, insane, nonsensical, odd, outlandish, preposterous, ridiculous, unreal, wild; outside, remote, slightNear Antonyms believable, conceivable, credible, earthly, imaginable, plausible; possible, potential; liableAntonyms likely, probable

4 not feeling sure about the truth, wisdom, or trustworthiness of someone or something dubious about a diet that claims I can eat all I want and still lose weight Synonyms distrustful, doubtful, hinky [slang], mistrustful, skeptical, suspicious, trustless, uncertain, unconvinced, undecided, unsettled, unsureRelated Words ambivalent, conflicted, equivocal; diffident, insecure; halting, hesitant, indecisive, irresolute, vacillating, waveringNear Antonyms assured, confident, sanguine, self-assured; decisive, determined, resoluteAntonyms certain, convinced, positive, sure