OPERCULUM
- a covering flap in plants, pl OPERCULA or OPERCULUMS [n OPERCULUMS or OPERCULA]
- an opercule (an anatomical part that serves as a lid or cover) [n OPERCULUMS]
- A structure that closes or covers an aperture, in particular
- A secreted plate that serves to close the aperture of a gastropod mollusk's shell when the animal is retracted
- A lidlike structure of the spore-containing capsule of a moss