Antonyms for dubious

doubtful:

positive, honest, believable, undoubted, doubtless, determined, Undoubtful, unquestionable, definite, reliable, likely, certain, unobscure, unambiguous, Indubious, sure, clear, trusty, aboveboard, trustworthy, probable, secure.

vague, unclear:

settled.

noun:

distinct, enthusiastic, eager, earthly, undoubted, keen, glad, self-assured, decided, unproblematic, unequivocal, manifest, perspicuous, inclined, convinced, Questionless, open-and-shut, hands down, unquestioning, potential, unquestioned, ready, plain, definitive, evident, willing, disposed, happy, imaginable, lucid.

Paraphrases for Dubious:

• Adjective :
  adverse, alarming, ambiguous, arguable, bad, bitter, bleak, borderline, certain, clear, concerned, confused, confusing, contentious, contestable, contested, contradictory, controversial, critical, dangerous, dark, debatable, deplorable, depressed, depressing, dire, disgusting, dismal, disputable, disputed, disquieting, disreputable, distressing, disturbing, dodgy, double, doubtful, dull, elusive, equivocal, evil, fishy, fluid, fragile, gloomy, grim, Half-hearted, hesitant, impaired, implausible, improbable, in-doubt, inappropriate, inconclusive, incredulous, insecure, lamentable, lonely, marginal, misbegotten, miserable, mistaken, mixed, moot, murky, mysterious, nasty, negative, objectionable, obscure, obvious, odd, ominous, opaque, painful, pathetic, pitiful, poor, precarious, probable, problematic, problematical, questionable, regrettable, reluctant, sad, Saddened, saddening, sceptical, serious, shadowy, shady, shaky, skeptical, sob, sobering, sombre, sorrowful, sorry, spurious, sticking, strange, sure, suspect, suspected, suspicious, tentative, tragic, troubling, ugly, unambiguous, uncertain, unclear, uncontroversial, underhand, unequivocal, unexplained, unfortunate, unhappy, unknown, unlikely, unpredictable, unreliable, unsavoury, unsettled, unsound, unstable, unsure, unusual, upset, vague, volatile, worrisome, worrying, wretched, wrong.