A door; especially, one of a pair of folding doors, or one
of the leaves of such a door.

A lid, plug, or cover, applied to an aperture so that by its
movement, as by swinging, lifting and falling, sliding, turning, or the
like, it will open or close the aperture to permit or prevent passage,
as of a fluid.

One of the pieces into which a capsule naturally separates
when it bursts.

One of the two similar portions of the shell of a diatom.

A small portion of certain anthers, which opens like a
trapdoor to allow the pollen to escape, as in the barberry.

One of the pieces or divisions of bivalve or multivalve
shells.