Try Our Apps


Avoid these words. Seriously.


[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.
Cite This Source
Examples from the Web for opercular
Historical Examples
British Dictionary definitions for opercular


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 the bony plate in certain gastropods covering the opening of the shell when the body is withdrawn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
Cite This Source
Word Origin and History for opercular



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
Cite This Source
opercular 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.
Cite This Source
opercular 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.
Cite This Source

Word of the Day

Nearby words for opercular

Difficulty index for operculum

Few English speakers likely know this word

Word Value for opercular

Scrabble Words With Friends