valve

A structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it.

Control consisting of a mechanical device for controlling the flow of a fluid.

Device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone.

One of the paired hinged shells of certain molluscs and of brachiopods.

The entire one-piece shell of a snail and certain other molluscs.