Adjacent Words

operculum definitions

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WordNet (r) 3.0 (2005)

n
1: a hard flap serving as a cover for the gill slits in fishes or (b) the opening of the shell in certain gastropods when the body is retracted

Merriam Webster's

noun (plural opercula; also -lums) Etymology: New Latin, from Latin, cover, from operire to shut, cover Date: 1681 1. a body process or part that suggests a lid: 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)

Oxford Reference Dictionary

n. (pl. opercula) 1 Zool. a a flaplike structure covering the gills in a fish. b a platelike structure closing the aperture of a gastropod mollusc's shell when the organism is retracted. c any of various other parts covering or closing an aperture, such as a flap over the nostrils in some birds. 2 Bot. a lidlike structure of the spore-containing capsule of mosses. Derivatives: opercular adj. operculate adj. operculi- comb. form. Etymology: L f. operire cover

Webster's 1913 Dictionary

Operculum O*per"cu*lum, n.; pl. L. Opercula, E. Operculums. [L., a cover or lid, fr. operire to cover.] 1. (Bot.) (a) The lid of a pitcherform leaf. (b) The lid of the urnlike capsule of mosses. 2. (Anat.) (a) Any lidlike or operculiform process or part; as, the opercula of a dental follicle. (b) The fold of integument, usually supported by bony plates, which protects the gills of most fishes and some amphibians; the gill cover; the gill lid. (c) The principal opercular bone in the upper and posterior part of the gill cover. 3. (Zo["o]l.) (a) The lid closing the aperture of various species of shells, as the common whelk. See Illust. of Gastropoda. (b) Any lid-shaped structure closing the aperture of a tube or shell.