oper·​cu·​lum | \ ō-ˈpər-kyə-ləm How to pronounce operculum (audio) \
plural opercula\ ō-​ˈpər-​kyə-​lə How to pronounce operculum (audio) \ also operculums

Definition of operculum

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)

Examples of operculum in a Sentence

Recent Examples on 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, 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.

First Known Use of operculum

1681, in the meaning defined at sense 1

History and Etymology for 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

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The first known use of operculum was in 1681

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opere citato

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Cite this Entry

“Operculum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/operculum. Accessed 13 Aug. 2022.

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More Definitions for operculum


oper·​cu·​lum | \ ō-ˈpər-kyə-ləm How to pronounce operculum (audio) \
plural opercula\ -​lə How to pronounce operculum (audio) \ also operculums

Medical Definition of operculum

: any of several parts of the cerebrum bordering the sylvian fissure and concealing the insula


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