A derogatory word used to describe a woman that is both overweight and unattractive. The word comes from a species of dinosaur known for being quite large and ugly, the Stegosaurus.
Also referred to someone, typically a woman, that is so skinny that her backbones stick out at least a half inch from her skin. Called this because looks like plates that'd you find on a stegosaurus
Whenever I see that stego bend over, I'm reminded of how hard it must have been for a T-rex to eat that!