Meaning of “mate” - Learner’s Dictionary

mate

noun [ C ] uk us /meɪt/
FRIEND UK informal

B1 a friend:

She's my best mate.
Pete was there with a couple of mates.
TALKING TO A MAN UK informal

You call a man 'mate' when you are speaking to him informally:

Thanks, mate.
ANIMAL

an animal's sexual partner:

Swans keep the same mate throughout their life.

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