1. (a.) Admitting of being questioned; inviting, or seeming to invite, inquiry.

2. (a.) Liable to question; subject to be doubted or called in question; problematical; doubtful; suspicious.

a bit thick a bit thin absurd ambiguous amoral arguable at issue beguiling beyond belief borderline catchy confutable conjectural conscienceless contestable controversial controvertible corrupt corrupted criminal crooked dark debatable deceiving deceptive delusive delusory deniable devious dishonest dishonorable disputable doubtable doubtful dubious dubitable equivocal evasive fallacious FALSE felonious fishy fly-by-night fraudulent hallucinatory hard of belief hard to believe hardly possible iffy ill-got ill-gotten illusive illusory immoral implausible improbable in dispute in doubt in dubio in question inconceivable incredible indirect insidious misleading mistakable moot more than doubtful not deserving belief not kosher obscure open to doubt open to question open to suspicion passing belief preposterous problematic problematical refutable ridiculous rotten shady shameless shifty sinister slippery speculative staggering belief suppositional suspect suspicious tall thick thin trickish tricksy tricky trustless unbelievable uncertain unconscienced unconscientious unconscionable unconvincing undependable underhand underhanded unearthly unethical ungodly unimaginable unlikely unprincipled unpromising unreliable unsavory unscrupulous unstraightforward unsure unthinkable untrustworthy untrusty unworthy of belief vague without remorse without shame