1350–1400; Middle English douteful.
doubtfully, adverbdoubtfulness, nounpredoubtful, adjectivepredoubtfully, adverbquasi-doubtful, adjectivequasi-doubtfully, adverbundoubtful, adjectiveundoubtfully, adverbundoubtfulness, noun
undetermined, unsettled, indecisive, dubious, problematic. 2.
unsure, indeterminate. 3.
irresolute, vacillating, hesitant. Doubtful, dubious, incredulous, skeptical
imply reluctance or unwillingness to be convinced. To be doubtful
about something is to feel that it is open to question or that more evidence is needed to prove it: to be doubtful about the statements of witnesses. Dubious
implies vacillation, unsureness, or suspicion: dubious about suggested methods of manufacture. Incredulous
means unwilling or reluctant to believe: incredulous at the good news. Skeptical
implies a general disposition to doubt or question: skeptical of human progress. 4.