VALVE

Definition

1. noun a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it.
2. noun device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone.
3. noun control consisting of a mechanical device for controlling the flow of a fluid.
4. noun the entire one-piece shell of a snail and certain other molluscs.
5. noun one of the paired hinged shells of certain molluscs and of brachiopods.