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Supposedly vs. Supposably


[dout-fuh l] /ˈdaʊt fəl/
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.
Origin of doubtful
1350-1400; Middle English douteful. See doubt, -ful
Related forms
doubtfully, adverb
doubtfulness, noun
predoubtful, adjective
predoubtfully, adverb
quasi-doubtful, adjective
quasi-doubtfully, adverb
undoubtful, adjective
undoubtfully, adverb
undoubtfulness, noun
1. 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. shady.
1, 2. certain.
Usage note
See doubt. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for doubtful
Contemporary Examples
Historical Examples
  • "I don't doubt it at all," said the doubtful Dromedary to everyone's surprise.

    The Royal Book of Oz L. Frank Baum
  • He said that there was plenty of fishing; but he said it in a tone which made me doubtful about his meaning.

    Days Off Henry Van Dyke
  • We might run down to the light-house by mid-day, while it is doubtful if we could reach the town until to-morrow morning.

    Jack Tier or The Florida Reef James Fenimore Cooper
  • At first he was doubtful whether so small an object could be a bird.

    The Western World W.H.G. Kingston
  • This, I fear, is a doubtful blessing, for it leads to a vast number of the birds being taken prisoner.

    Birds of the Plains Douglas Dewar
British Dictionary definitions for doubtful


unlikely; improbable
characterized by or causing doubt; uncertain: a 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
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
Derived Forms
doubtfully, adverb
doubtfulness, noun
Usage note
It was formerly considered correct to use whether after doubtful (it is doubtful whether he will come), but now if and that are also acceptable
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for doubtful

late 14c., from doubt (n.) + -ful. Related: Doubtfully; doubtfulness.

Online Etymology Dictionary, © 2010 Douglas Harper
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