a person of the opposite sex mainly used for sexual activities. relations don't typically include much more interaction than weekend/late night phone calls and rendezvous.
mike: "hey dude what are you doing tonight?"
brian: "i'm getting blacked out then hitting up my crush piece for some action."
a word describing a female in which you dont have a relationship with, because you are keeping in the hook up or friend zone incase a hotter girl comes along.