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