Operculars

Part of speech: noun

Definitions

1. Relating to or resembling structures that cover or protect
2. describing features of certain fish anatomy that involve external bony coverings
3. characterizing protective membranes in various organisms that serve a specific function

Etymology: "Operculars" is simply the plural of "opercular," an adjective used in ichthyology to describe the bony gill covers of fish and the structures tied to them. The plural form appears when a writer refers to several such features at once, as in discussions of multiple fish species or of paired gill-cover bones. The adjective "opercular" goes back to the Latin "operculum," meaning a lid or cover, formed from "operire," to cover over. The Latin noun gave English a ready-made term for anything that serves as a lid, and naturalists applied the adjective to the gill covers because each one acts as a flap shielding the gills.