operculum

noun oper·cu·lum \ ō-ˈpər-kyə-ləm \

Definition of operculum

plural opercula play \ō-ˈpər-kyə-lə\ also operculums

1 : a body process or part that suggests a lid: such as

a : a horny or shelly plate on the posterior dorsal surface of the foot in many gastropod mollusks that closes the shell when the animal is retracted

b : the covering of the gills of a fish — see fish illustration

2 : a lid or covering flap (as of a moss capsule)

Recent Examples of operculum from the Web

Scallops, for example, showcase a complex system of camouflage, with a colored shell on top and a white shell on the bottom; most gastropods are born with trapdoor-like devices called an operculum, which protect them from predators.

— susan glaser, cleveland.com, "In search of the perfect shell on Florida's Sanibel Island (photos)," 10 Jan. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'operculum.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of operculum

borrowed from New Latin, going back to Latin, "cover, lid," from operīre "to shut, close, cover" (from op-, variant of ob- ob- + pre-Latin *-wer-je- "open or close," as specified by a prefix, going back to Indo-European *Hu̯er-) + -culum, instrumental suffix (going back to Indo-European *-tlom) — more at aperient

NEW! Time Traveler

First Known Use: 1681

in the meaning defined at sense 1

See Words from the same year