(Chapter 3) Footnote 59:

The Greek and Latin terminology originally used a cup metaphor for the bone socket. Kotu/lh and kotulhw/n denote anything cup-shaped; o)cu/bafon is a small, shallow vinegar-saucer, as is Lat. acetabulum, also used as a ⅛ pint measure. Pyxis, orig. Greek for a small medicine box, came in Lat. to mean any small vessel; bucella, lit. “little cheek,” is cognate to Eng. buccal.