[ oh-pur-kyuh-luh m ]
/ oʊˈpɜr kyə ləm /

noun, plural o·per·cu·la [oh-pur-kyuh-luh] /oʊˈpɜr kyə lə/, o·per·cu·lums.

Botany, Zoology. a part or organ serving as a lid or cover, as a covering flap on a seed vessel.
  1. the gill cover of fishes and amphibians.
  2. (in many gastropods) a horny plate that closes the opening of the shell when the animal is retracted.

Origin of operculum

1705–15; < New Latin, Latin: lid, cover, equivalent to oper(īre) to cover + -culum -cule2

Related forms

o·per·cu·lar, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for opercular

British Dictionary definitions for opercular


/ (əʊˈpɜːkjʊləm) /

noun plural -la (-lə) or -lums

  1. the hard bony flap covering the gill slits in fishes
  2. the bony plate in certain gastropods covering the opening of the shell when the body is withdrawn
botany the covering of the spore-bearing capsule of a moss
biology any other covering or lid in various organisms

Derived Forms

opercular or operculate (əʊˈpɜːkjʊlɪt, -ˌleɪt), adjective

Word Origin for operculum

C18: via New Latin from Latin: lid, from operīre to cover
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Medicine definitions for opercular


[ ō-pûrkyə-ləm ]

n. pl. o•per•cu•lums

Something resembling a lid or cover.
The portions of the frontal, parietal, and temporal lobes covering the insula.
The mucus sealing the endocervical canal of the uterus after conception.
The attached flap in cases of torn retinal detachment.
The mucosal flap partially or completely covering an unerupted tooth.

Related forms

o•percu•lar (-lər) adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for opercular


[ ō-pûrkyə-ləm ]

Plural opercula operculums

A lid or flap covering an opening, such as the gill cover in some fish or the horny flap covering the opening of a snail.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.