adjective
doubtful
DOWT-fuhl
adjective
1
Not certain to happen or be true; uncertain.
"It's doubtful she'll finish the report by tonight."
"The outcome of the vote remains doubtful."
2
Feeling or showing doubt about something.
"He gave a doubtful look when I explained my plan."
"She sounded doubtful about the investment's chances."
3
Of questionable honesty or reliability.
"The source turned out to be doubtful at best."
How to Use Doubtful
Learner’s notesIn plain EnglishNot sure — used for people who aren't sure, or situations that aren't likely to happen.
Common pairings
doubtful about
it is doubtful that
doubtful outcome
Word Forms
more doubtful comparative, doubtfuls plural, most doubtful superlative
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Etymology
From Middle English doutfull — built from doubt plus -ful, "full of."