The Collaborative International Dictionary
Osmaterium
Osmaterium \Os`ma*te"ri*um\, n.; pl. Osmateria. [NL., fr. Gr. ? smell.] (Zo["o]l.) One of a pair of scent organs which the larv[ae] of certain butterflies emit from the first body segment, either above or below.
Wiktionary
osmaterium
n. (alternative form of osmeterium English)