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

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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

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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

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

Synonym Usage

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

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

Etymology

Origin of doubtful

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

Explanation

When you're doubtful about something, you're not sure about it. You might feel doubtful about the picnic you've planned if the forecast calls for torrential rain. Whether you're uncertain, undecided, or suspicious, you can describe yourself as doubtful. You'll be doubtful about your taxi driver's sense of direction when you pass the same building for the third time. You might also be doubtful about whether or not to try skydiving. Doubtful means "full of doubt," and doubt is from the Old French doter, "doubt or be afraid," with a Latin root, dubitare, "to question, hesitate, or waver in opinion."

Example Sentences

See Examples For:

doubtful

Warsh has vowed the Fed will vanquish inflation and meet its 2% goal, but Wall Street investors have grown more doubtful.

From MarketWatch ● Jul. 31, 2026

It’s doubtful that eliminating quarterly reports will save much, if any, money.

From Los Angeles Times ● Jul. 8, 2026

I speculate that Martha Jefferson’s death was in Thomas’s mind when, in the “Notes,” he mentioned “those numberless afflictions, which render it doubtful whether heaven has given life to us in mercy or in wrath.”

From The Wall Street Journal ● Jun. 26, 2026

So, as Jackson wrote, it’s doubtful that the Constitution actually requires this unrealistic level of contractual clarity.

From Slate ● Jun. 23, 2026

It is doubtful if any father ever was more insane about an offspring.

From "Cheaper by the Dozen" by Frank B. Gilbreth Jr. and Ernestine Gilbreth Carey

Related Words

• debatable
• dicey
• dubious
• hazy
• indecisive
• insecure
• precarious
• problematic
• suspicious
• uncertain
• undecided
• uneasy
• unsettled
• unstable
• unsure