ac·e·tab·u·lum 
(ăs′ĭ-tăbyə-ləm)
(ăs′ĭ-tăbyə-ləm)n. pl. ac·e·tab·u·la (-lə)
1. Anatomy The cup-shaped cavity at the base of the hipbone into which the ball-shaped head of the femur fits.
2. Zoology A cavity or socket in the body of an insect into which an appendage fits.
3. Zoology A cup-shaped structure, such as the sucker of a tapeworm or leech.
[Latin acētābulum, vinegar cup, from acētum, vinegar; see ACETUM.]
ac′e·tabu·lar (-lər) adj.