acetabulum

< /ˌæs ɪˈtæb yə lə/.

1. Anatomy. the socket in the hipbone that receives the head of the thighbone.
2. Zoology. any of the suction appendages of a leech, octopus, etc.

noun plural -la (-lə)

1. the deep cuplike cavity on the side of the hipbone that receives the head of the thighbone
2. a round muscular sucker in flatworms, leeches, and cephalopod molluscs
3. the aperture in the thorax of an insect that holds the leg

n. pl. ac•e•tab•u•la (-lə)

1. The cup-shaped cavity at the base of the hipbone into which the ball-shaped head of the femur fits.cotyloid cavity