A friend that is not the same gender as you.
ie: a boy's friendi would be girl.
This word is used when trying to explain the gender of a friend without having to go into too much detail. It saves time when trying to tell a story and can distinguish between a boyfriend and a boy friend, or girlfriend and girl friend.
Joe: "Bob, stop acting like you have a girlfriend."
Bob: "Not a girlfriend, just a friend that's a girl."
Joe: "Oh, you mean a friendi."