[du.bi.ous] adj [L dubius, fr. dubare to vacillate; akin to L duo two--more at two] (1548) 1: giving rise to uncertainty: as a: of doubtful promise or outcome "felt that our plan was a little ~" b: questionable or suspect as to true nature or quality "the practice is of ~ legality" "the ~ honor of being the world's biggest polluter"
2: unsettled in opinion: doubtful "I was ~ about the plan" syn see doubtful -- du.bi.ous.ly adv -- du.bi.ous.ness n