As a noun brainwasher
is agent noun of brainwash; one who brainwashes.
As a verb brainwashes is
Other Comparisons: What's the difference?
An effect upon one's memory, belief, or ideas.
To affect one's mind by using extreme mental pressure or any other mind-affecting process. (i.e. hypnosis)
(figuratively, dated) To take from an electronically controlled machine its stored-up information; to erase a computer's programming. (1960)