Definition: The lid of a pitcherform leaf.
Definition: The lid of the urnlike capsule of mosses.
Definition: Any lidlike or operculiform process or part; as, the
opercula of a dental follicle.
Definition: 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.
Definition: The principal opercular bone in the upper and posterior
part of the gill cover.
Definition: The lid closing the aperture of various species of
shells, as the common whelk. See Illust. of Gastropoda.
Definition: Any lid-shaped structure closing the aperture of a tube
or shell.
