Subject to, or causing doubt. / Experiencing or showing doubt, sceptical. / Undecided or of uncertain outcome. / (obsolete) Fearsome, dreadful. / Improbable or unlikely.

A doubtful person or thing.

The state or quality of being doubtful; doubt; uncertainty.

plural of doubtfulness

plural of doubtful

(uncountable, countable) Disbelief or uncertainty (about something); (countable) a particular instance of such disbelief or uncertainty. / (countable, obsolete or India) A point of uncertainty; a query.

(transitive, intransitive) To be undecided about; to lack confidence in; to disbelieve, to question. / (transitive, archaic) To harbour suspicion about; suspect.

without a doubt; surely.

Third-person singular simple present indicative form of doubt

plural of doubt