an occasion when you meet someone, or do something with someone you do not know:
She didn't remember our encounter last summer.
Bernstein began training the young musician after a chance encounter at a concert (=a meeting that happened by chance).
casual sexual encounters (=occasions when people have sex)
hostile encounters between supporters of rival football teams
an occasion when you meet or experience something
a child's first encounter with books
a close encounter with a snake (=a frightening situation in which you get too close to something)