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n. pl. os·me·te·ri·a (-tîr′ē-ə)
An eversible organ behind the head of certain caterpillars, containing strong-smelling chemicals that deter predators.

[New Latin osmētērium, from Greek osmē, smell.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


n, pl -ria (-rɪə)
(Zoology) zoology a gland in some caterpillars that secretes foul-smelling substances to deter predators
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
The caterpillar is similarly impressive in pale green, black and orange and when threatened it everts a pair of orange tentacles (technically the osmeterium) behind the head that smell very nasty.
This brightly colored gland, called the osmeterium, mimics a snake's tongue, and, when extended, gives off a foul odor to boot.
Las orugas de esta familia poseen una glandula retractil en forma de "Y" llamada osmeterium, de color amarillo o anaranjado, que sirve de defensa (VELEZ & SALAZAR, 1991).
Many caterpillars have an osmeterium, a forked organ behind the head that emits a foul odor when the caterpillar is threatened.
The ultrastructure of the osmeterium and the nature of its secretion in Pa pilio larvae (Lepidoptera).