Dictionary.com
Thesaurus.com
Synonyms

doubtful

American  
[dout-fuhl] / ˈdaʊt fəl /

adjective

  1. of uncertain outcome or result.

    Synonyms:
    problematic, dubious, indecisive, unsettled, undetermined
    Antonyms:
    certain
  2. admitting of or causing doubt; uncertain; ambiguous.

    Synonyms:
    indeterminate, unsure
    Antonyms:
    certain
  3. unsettled in opinion or belief; undecided; hesitating.

    Synonyms:
    hesitant, vacillating, irresolute
  4. of equivocal or questionable character.

    His tactics are highly doubtful.

    Synonyms:
    shady

doubtful British  
/ ˈdaʊtfʊl /

adjective

  1. unlikely; improbable

  2. characterized by or causing doubt; uncertain

    a doubtful answer

  3. unsettled; unresolved

  4. of questionable reputation or morality

  5. having reservations or misgivings

  6. (of a sportsperson) not likely to be fit enough to play or take part

"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

noun

  1. a person who is undecided or uncertain about an issue

  2. a sportsperson who is not likely to be fit enough to play or take part

"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

Usage

See doubt.

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

Related Words

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.

Other Word Forms

  • doubtfully adverb
  • doubtfulness noun
  • predoubtful adjective
  • predoubtfully adverb
  • quasi-doubtful adjective
  • quasi-doubtfully adverb
  • undoubtful adjective
  • undoubtfully adverb
  • undoubtfulness noun

Etymology

Origin of doubtful

First recorded in 1350–1400, doubtful is from the Middle English word douteful. See doubt, -ful

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

If there is enough private support in Washington, which is doubtful, the Kennedy Center could become a privately funded model similar to its peers around the country.

From The Wall Street Journal

It’s doubtful that any trading algorithms kicked in, except those that might have been keyed to a sharp reversal of trading sentiment from earlier in the week, when it was pretty sour.

From Los Angeles Times

They argued the seizure was therefore "heavily aggravated by the circumstances and appears to have had a doubtful or improper motive".

From BBC

And the recent examples of private loans held near cost that were marked down dramatically shortly thereafter might have investors in a doubtful frame of mind.

From The Wall Street Journal

Following the first round of US-brokered talks in Abu Dhabi last month, Ukrainians were doubtful any deal could be struck with Moscow.

From Barron's