A woman with a perfect body, filled-in in places that are, by nature, designed to attract the opposite sex, such as the thighs, the hips, the breasts, and the most lovely part of all, the booty.
When a girl's body has weight on it, but not ugly, out of shape weight. More like medium and curvy. A round behind and firm, full legs is considered thick.
That girl has a very pretty face, but her behind is flat so she's far from thick.