1) A female jock.
2) A chick who excels in athletics but isn't very bright and is somewhat an airhead.
1) Act of a guy losing to a girl 1on1 in a sport.
Me: See that jilk over there?
Friend: Yea I recognize her. She practically lives in the fucking gym man. I hear she plays soccer,softball,basketball,tennis and does karate.
Me: She's dumb as rocks, but I bet she can beat your ass in most sports!
Me: Ha ha, what a loser! I can't believe that girl jilked you. You must feel like an idiot losing 1on1 like that to a girl in basketball.
Friend: Yea, I pretty much hate my life right now.