/ Dictionary / Index D doubtful: Meaning and Definition of Find definitions for: doubt•ful Pronunciation: (dout'ful), [key] — adj. of uncertain outcome or result. admitting of or causing doubt; uncertain; ambiguous. unsettled in opinion or belief; undecided; hesitating. of equivocal or questionable character: His tactics are highly doubtful. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: doubtful (Thesaurus) doubt doubting Thomas Related Content Daily Word Quiz: designate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language