to get to know each other; to make acquaintance
大学で知り合った友人と今も付き合っている。
I'm still friends with someone I met at university.
大学で知り合って、もう十年の付き合いになる。
We got to know each other in college, and it's been ten years now.
彼とは留学先で知り合っている。
I already know him from when I studied abroad.