Meaning of “brainwash” - Learner’s Dictionary

brainwash

verb [ T ] uk us /ˈbreɪnwɒʃ/

to make someone believe something by telling them that it is true many times:

[ + into + doing sth ] Advertising often brainwashes people into buying things they do not really need.
brainwashing noun [ U ]

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