/ ˈdaʊtfl; NAmE / adjective
1.
doubtful (about sth) | doubtful (about doing sth) ( of a person ) not sure; uncertain and feeling doubt
SYN dubious :
Rose was doubtful about the whole idea.
He was doubtful about accepting extra work.
2.
doubtful (if / that / whether ... ) unlikely; not probable :
It's doubtful if this painting is a Picasso.
With her injuries it's doubtful that she'll ever walk again.
It's doubtful whether the car will last another year.
He is injured and is doubtful for the game tomorrow (= unlikely to play) .
3.
[ not usually before noun ] ( of a thing ) uncertain and likely to get worse :
At the beginning of the war things were looking very doubtful.
4.
[ only before noun ] of low value; probably not genuine or of a quality that you can rely on
SYN dubious :
This wine is of doubtful quality.
► doubt·ful·ly / -fəli; NAmE / adverb