nounpl. -·la or -·lums
any of various covering flaps or lidlike structures in plants and animals; specif.,
- the bony covering protecting the gills of fishes
- in many gastropods, the horny plate serving to close the shell when the animal is retracted
- the lidlike structure of a spore case in mosses
- the lidlike structure of a pitcher-shaped leaf
Origin of operculumModern Latin from L, lid, diminutive from operire, to close, shut: for Indo-European bases see ob- and aperture
nounpl. o·per·cu·la, or o·per·cu·lums
Biology A lidlike structure covering an opening, especially:
a. A bony plate that covers and protects the gills of most bony fishes. Also called gill cover .
b. A horny or calcareous plate attached to the foot of most larval and many adult gastropods, used to close the aperture when the animal retracts into its shell.
c. A covering at the top of the spore capsule of most mosses, falling off when mature spores are released.
Origin of operculumLatin lid from operīre to cover ; see wer-4 in Indo-European roots.
- A covering flap or lidlike structure in plants and animals, such as a gill cover
From Latin operculum.