Meaning of operculum

o•per•cu•lum

Pronunciation: (ō-pûr'kyu-lum), [key]
— pl. -la -lums.
  1. 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. See diag. underfish.
    2. (in many gastropods) a horny plate that closes the opening of the shell when the animal is retracted.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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