from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Subject to or causing doubt: a doubtful claim; doubtful prospects.
- adj. Experiencing or showing doubt: Doubtful that the cord would hold, we strengthened it.
- adj. Of uncertain outcome; undecided.
- adj. Raising doubts as to legitimacy, honesty, or respectability; suspicious: the candidate's doubtful past. See Usage Note at doubt.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Subject to, or causing doubt
- adj. Experiencing or showing doubt, sceptical
- adj. Undecided or of uncertain outcome
- adj. Fearsome, dreadful.
- adj. Improbable or unlikely
- adj. Suspicious, or of dubious character
- adj. Unclear or unreliable
from the GNU version of the Collaborative International Dictionary of English
- adj. 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.
- adj. Admitting of doubt; not obvious, clear, or certain; questionable; not decided; not easy to be defined, classed, or named.
- adj. Characterized by ambiguity; dubious
- adj. Of uncertain issue or event.
- adj. Fearful; apprehensive; suspicious.
from The Century Dictionary and Cyclopedia
- Full of doubt; having doubt; not settled in opinion.
- Causing doubt; dubious; ambiguous; uncertain; not distinct in character, meaning, or appearance; vague: as, a doubtful expression; a doubtful hue.
- Admitting of or subject to doubt; not obvious, clear, or certain; questionable.
- Of uncertain issue; precarious; shifting.
- Of questionable or suspected character.
- Fearful; apprehensive; suspicious.
- Indicating doubt; disturbed by doubt.
- In prosody, variable in quantity; capable of being pronounced or measured either as a long or as a short; common; dichronous.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adj. open to doubt or suspicion
- adj. fraught with uncertainty or doubt
- adj. unsettled in mind or opinion
From doubt + -ful. (Wiktionary)