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[oh-pur-kyuh-luh m] /oʊˈpɜr kyə ləm/
noun, plural opercula
[oh-pur-kyuh-luh] /oʊˈpɜr kyə lə/ (Show IPA),
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
opercular, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for opercula
Historical Examples
  • It should be mentioned that the Serpulacea are provided with opercula.

    A Conchological Manual George Brettingham Sowerby
  • The figures represent some of the commoner types of opercula.

    The Sea-beach at Ebb-tide Augusta Foote Arnold
  • These are the drum-covers or opercula, from beneath which the sound issues.

  • It was shaped and ornamentally carved and painted to represent a wood-worm and inlaid along the rounded upper edge with opercula.

  • The opercula vary to a great extent in the different genera; in some cases they are calcareous, in others cartilaginous.

    The Sea-beach at Ebb-tide Augusta Foote Arnold
  • I have already pointed out the few very trifling points, in which the opercula of the two species differ.

  • The opercula of various shells differ in the first place as to their chemical composition.

    A Conchological Manual George Brettingham Sowerby
  • The third section contains the following genera of land shells with opercula.

    A Conchological Manual George Brettingham Sowerby
  • Two other genera of land shells are provided with opercula, and consequently might be confounded with this genus.

    A Conchological Manual George Brettingham Sowerby
  • The opercula of multivalve shells are composed of two or four pieces, which are called the opercular valves.

    A Conchological Manual George Brettingham Sowerby
British Dictionary definitions for opercula


noun (pl) -la (-lə), -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 the bony plate in certain gastropods covering the opening of the shell when the body is withdrawn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, operculate (əʊˈpɜːkjʊlɪt; -ˌleɪt) adjective
Word Origin
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
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Word Origin and History for opercula



1713, from Latin operculum "cover, lid," from operire "to cover, close" (see weir), with instrumental suffix *-tlom. Related: Opercular.

Online Etymology Dictionary, © 2010 Douglas Harper
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opercula in Medicine

operculum o·per·cu·lum (ō-pûr'kyə-ləm)
n. pl. o·per·cu·lums or o·per·cu·la (-lə)

  1. Something resembling a lid or cover.

  2. The portions of the frontal, parietal, and temporal lobes covering the insula.

  3. The mucus sealing the endocervical canal of the uterus after conception.

  4. The attached flap in cases of torn retinal detachment.

  5. The mucosal flap partially or completely covering an unerupted tooth.

o·per'cu·lar (-lər) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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opercula in Science
Plural opercula or 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 © 2002. Published by Houghton Mifflin. All rights reserved.
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