Semi-friends are guys that you meet on a regular basis, because you share the same group of people. For instance, the people you met after you joined a sports-club or a fraternity could be your semi-friends. The reason why you meet these people is often different from just hanging out together. a semi-friendship might also be called an arranged friendship.

someone you have the relationship with which is a split between an acquaintance and friend, but someone whos name you don't forget and say hi to when you walk by.