doubtful

adj. 1 feeling doubt. 2 causing doubt. 3 unreliable.  doubtfully adv. Doubtfulness n.

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.