acetabulum

noun

1. The bony cup of the hip bone which receives the head of the femur.

   “Holonyms: hip joint; hip bone < pelvis”

2. The cavity in which the leg of an insect is inserted at its articulation with the body.
3. A sucker of the sepia or cuttlefish and related animals.
4. The large posterior sucker of the leeches.
5. One of the lobes of the placenta in ruminating animals.
6. A vinegar saucer, especially (historical) in ancient Roman contexts.
7. (historical)A Roman unit of liquid measure reckoned as the volume of 2½ Roman ounces of wine and equivalent to about 66 mL although differing slightly over time.