1) the female object of your enduring and persistent efforts who has never found it in her heart to part her knees for you. 2) a tease 3) the one that got away. 4) the one that never goes away, but will not put out for you today or any day.
Guy 1: I just made plans to grab drinks with Jessica from marketing. Guy 2: Don't bother, I've been trying to unravel that Gordian Twat for over a year. I keep telling myself she's a lesbian so that I don't have to kick her out of the spank bank.