Dictionary Home »
Dictionary Definitions » osmeterium
osmeterium
(ŏzˌmĭ-tîrˈē-əm)
noun pl. os·me·te·ri·a (-tîrˈē-ə) An eversible glandular sac on the first thoracic segment of many caterpillars that secretes an unpleasant-smelling substance to ward off predators.