osmeterium

noun

os·​me·​te·​ri·​um ˌäz-mə-ˈtir-ē-əm 

plural osmeteria ˌäz-mə-ˈtir-ē-ə 

: a protrusible glandular process of swallowtail larvae that emits a disagreeable odor for defensive purposes

Word History

Etymology

alteration of earlier osmaterium, probably from Greek osma-, stem of osmáomai, osmâsthai "to smell" (derivative of osmḗ "smell, odor") + -tērion, suffix of containers and locations (derivative of -tēr, agent suffix) — more at osmium

Note: Term introduced in William Kirby and William Spence's Introduction to Entomology, vol. 2 (London, 1817), p. 244: "I shall next beg your attention to those insects that emit their smell from particular organs. Of these, some are furnished with a kind of scent-vessels, which I shall call osmateria…."

First Known Use

1817, in the meaning defined above