questionable

questionable (Dubious), adjective ambiguous, at issue, contestable, controversial, controvertible, debatable, disputable, doubtable, doubtful, dubious, enigmatical, equivocal, experimental, fallible, hard to believe, hardly possible, improbable, inconceivable, indefinite, indeterminate, in dispute, in question, moot, more than doubtful, not axiomatic, objectionable, open to doubt, open to question, perplexing, puzzling, speculative, suspect, suspicious, tentative, unauthentic, unconvincing, undecided, undetermined, unlikely, unreliable, unsettled, unsound, unsure, unsustainable, untrustworthy, vague

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questionable (Unethical), adjective corrupt, dishonorable, disreputable, ill-gotten, immoral, shady, unconscionable, underhanded, unprincipled, unscrupulous, untrustworthy

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See also: blameworthy, contestable, controversial, debatable, disputable, doubtful, dubious, dubitative, equivocal, fallacious, implausible, indefinite, lewd, ludicrous, moot, outrageous, problematic, speculative, tentative, unbelievable, undecided, unethical, unscrupulous, unsound, unsustainable, untenable, untrustworthy, vague