adjective
- 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.
adjective
- unlikely; improbable
- characterized by or causing doubt; uncertaina doubtful answer
- unsettled; unresolved
- of questionable reputation or morality
- having reservations or misgivings
- (of a sportsperson) not likely to be fit enough to play or take part
noun
- a person who is undecided or uncertain about an issue
- a sportsperson who is not likely to be fit enough to play or take part
adj.late 14c., from doubt (n.) + -ful. Related: Doubtfully; doubtfulness.