du·bi·ous / ˈd(y)oōbēəs/ • adj. 1. hesitating or doubting: Alex looked dubious, but complied.2. not to be relied upon; suspect: extremely dubious assumptions. ∎  morally suspect: timesharing has been brought into disrepute by dubious sales methods. ∎  of questionable value: she earned the dubious distinction of being the lowest-paid teacher in the nation.DERIVATIVES: du·bi·ous·ly adv.du·bi·ous·ness n.

dubious XVI. — L. dubiōsus, f. dubium doubt, sb. use of n. of dubius doubtful, obscurely f. duo TWO, and meaning ‘hesitating between two alternatives’; cf. DOUBT.
So dubiety XVIII. — late L. dubietās.