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