Bedeutung von “whom” — Learner’s Dictionary

whom

pronoun us uk /huːm/ formal
With whom were you sitting?That's the man about whom I was speaking.On whom does the ultimate responsibility fall?He does not know whom to believe.The girl to whom you spoke is my cousin.

B2 used instead of 'who' as the object of a verb or preposition:

I met a man with whom I used to work.

(Definition von “whom” aus dem Cambridge Learner's Dictionary © Cambridge University Press)