From Biology-Online Dictionary | Biology-Online Dictionary


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 [i. 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.