Meaning of “doubt” - Learner’s Dictionary

doubt

verb [ T ] uk us /daʊt/
FEEL UNCERTAIN

B2 to feel uncertain about something or think that something is not probable:

[ + (that) ] I doubt that I'll get the job.
I doubt if/whether he'll win.
NOT BELIEVE

to not believe someone or something:

Do you have any reason to doubt her?

(Definition of “doubt verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)