m]
ni(on) an ox-head, equiv. to Gk bou- (s. of boûs) ox + krāníon cranium 
bucranium
decorative motif representing an ox killed in religious sacrifice. The motif originated in a ceremony wherein an ox's head was hung from the wooden beams supporting the temple roof; this scene was later represented, in stone, on the frieze, or stone lintels, above the columns in Doric temples.
Learn more about bucranium with a free trial on Britannica.com.