A remarkably attractive young woman; i.e. skinny, long-legged, well-dressed, and potentially a high fashion model.
1. Check out the fit bird at eight o'clock.
2. This place is a bummer, man--I haven't seen a fit bird in the joint since we've been here.
British English for Hot Chick
Brit: Me and my mates are going to check out the talent and see if there are any fit birds.
Yank: Aight, I think there are some hot chicks.