Pronunciation: (dout'ful), [key]
1. of uncertain outcome or result.
2. admitting of or causing doubt; uncertain; ambiguous.
3. unsettled in opinion or belief; undecided; hesitating.
4. of equivocal or questionable character: His tactics are highly doubtful.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.