Definition of fool verb from the Oxford Advanced Learner's Dictionary

fool

verb

fuːl

fuːl

1 [transitive] to trick somebody into believing something that is not truefool somebody You don't fool me!She certainly had me fooled—I really believed her!fool yourself You're fooling yourself if you think none of this will affect you.fool somebody into doing something Don't be fooled into thinking they're going to change anything.2 [intransitive] to say or do stupid or silly things, often in order to make people laughfool (about/around) Stop fooling around and sit down!fool (about/around) with something If you fool about with matches, you'll end up getting burned.

Idioms

you could have fooled me

(informal) used to say that you do not believe something that somebody has just told you‘I'm trying as hard as I can!’ ‘You could have fooled me!’

Phrasal verbs

fool around

1 (British English also fool about) to waste time instead of doing something that you should be doing

Synonym

mess around2 fool (with somebody) to have a sexual relationship with another person's partner; to have a sexual relationship with somebody who is not your partner

Synonym

mess aroundShe's been fooling around with a married man.