plural of mate
"The two old sailing ships drifted apart, leaving their crews without mates to share the journey home."
Third-person singular simple present indicative form of mate
"The fish swims in search of a partner to mate during the breeding season."
In plain English: To mate means to have sex with someone of the opposite gender for reproduction.
"The two dogs started to mates when they met at the park fence."
Friendly; having a friendship (with).
"The two neighbors became mates after sharing stories on their front porch every evening."
In plain English: Mates describes people who are close friends and hang out together often.
"They played badminton with their mates at the park yesterday afternoon."
The word mates likely entered English either as a borrowed term for a companion derived from the Hungarian nickname Mátés or from the Catalan word for scrubby bushes. In both cases, it was adopted to describe close friends rather than its original specific meanings in those languages.