Valve - Definition

n 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
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