noun pl. opercula or operculums
any of various covering flaps or lidlike structures in plants and animals; specif.,
- the bony covering protecting the gills of fishes: see fish,
- in many gastropods, the horny plate serving to close the shell when the animal is retracted
- the lid of spore cases in mosses
- the lid of a pitcher-shaped leaf
Origin:
ModL < L, lid, dim. < operire, to close, shut: for IE bases see ob- & aperture