1. 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. Methinks i should know you, and know this man; yet i am doubtful. (Shak) With doubtful feet and wavering resolution. (Milton)
2. 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. Beauty is but a vain and doubtful good. (Shak) Is it a great cruelty to expel from our abode the enemy of our peace, or even the doubtful friend E, one as to whose sincerity there may be doubts? (Bancroft)
3. Characterised by ambiguity; dubious; as, a doubtful expression; a doubtful phrase.
4. Of uncertain issue or event. We . . . Have sustained one day in doubtful fight. (Milton) The strife between the two principles had been long, fierce, and doubtful. (Macaulay)
5. Fearful; apprehensive; suspicious. I am doubtful that you have been conjunct And bosomed with her. (Shak)
Synonym: Wavering, vacillating, hesitating, undetermined, distrustful, dubious, uncertain, equivocal, ambiguous, problematical, questionable.