1911 Encyclopædia Britannica/Acetabulum

ACETABULUM, the Latin word for a vinegar cup, an ancient Roman vessel, used as a liquid measure (equal to about half a gill); it is also a word used technically in zoology, by analogy for certain cup-shaped parts, e.g. the suckers of a mollusc, the socket of the thigh-bone, &c.; and in botany for the receptacle of Fungi.