doubtful

1 not feeling sure about the truth, wisdom, or trustworthiness of someone or something he was doubtful about the decision to complete the project despite its mounting problems Synonyms distrustful, dubious, hinky [slang], mistrustful, skeptical, suspicious, trustless, uncertain, unconvinced, undecided, unsettled, unsure Related Words ambivalent, conflicted, equivocal; diffident, insecure; halting, hesitant, indecisive, irresolute, vacillating, wavering Phrases on the fence Near Antonyms assured, confident, sanguine, self-assured; decisive, determined, resolute Antonyms certain, convinced, positive, sure

2 giving good reason for being doubted, questioned, or challenged the election results were highly doubtful, so an investigation was begun Synonyms debatable, disputable, dodgy [chiefly British], doubtable, dubious, dubitable, equivocal, fishy, problematic (also problematical), queer, questionable, shady, shaky, suspect, suspicious Related Words alleged, so-called, supposed; moot; ambiguous, open, unclear; uncertain, undecided, undetermined; far-fetched, flimsy, improbable, unlikely, weak Near Antonyms decisive, definitive; clear, obvious, open-and-shut, positive Antonyms certain, hands-down, incontestable, indisputable, indubitable, questionless, sure, undeniable, undoubted, unproblematic, unquestionable

3 not likely to be true or to occur our winning the championship increasingly looks like a doubtful outcome Synonyms improbable, dubious, 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 open to question or dispute a doubtful claim to the property Synonyms arguable, controvertible, disputable, doubtable, debatable, issuable, moot, negotiable, questionableRelated Words contradictable, refutable; controversial, debated, disputed; dubious, iffy, inconclusive, indecisive, problematic (also problematical), shaky, uncertain; academic (also academical), hypothetical, speculative, theoretical (also theoretic); ambiguous, equivocalNear Antonyms irrefutable; definite; unambiguous, unequivocal; absolute, clear, conclusive, decisive; uncontested, undisputedAntonyms accomplished, certain, hands-down, inarguable, incontestable, incontrovertible, indisputable, indubitable, irrefragable, positive, questionless, settled, sure, unanswerable, unarguable, unchallengeable, undebatable, undeniable, unquestionable