(1):
(a.) Not settled in opinion; undetermined; wavering; hesitating in belief; also used, metaphorically, of the body when its action is affected by such a state of mind; as, we are doubtful of a fact, or of the propriety of a measure.
(2):
(a.) Admitting of doubt; not obvious, clear, or certain; questionable; not decided; not easy to be defined, classed, or named; as, a doubtful case, hue, claim, title, species, and the like.
(3):
(a.) Characterized by ambiguity; dubious; as, a doubtful expression; a doubtful phrase.
(4):
(a.) Fearful; apprehensive; suspicious.
(5):
(a.) Of uncertain issue or event.