Definitions of valve

  1. control consisting of a mechanical device for controlling the flow of a fluid
  2. device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
  3. A door; especially, one of a pair of folding doors, or one of the leaves of such a door.
  4. A lid, plug, or cover, applied to an aperture so that by its movement, as by swinging, lifting and falling, sliding, turning, or the like, it will open or close the aperture to permit or prevent passage, as of a fluid.
  5. One or more membranous partitions, flaps, or folds, which permit the passage of the contents of a vessel or cavity in one direction, but stop or retard the flow in the opposite direction; as, the ileocolic, mitral, and semilunar valves.
  6. One of the pieces into which a capsule naturally separates when it bursts.
  7. One of the two similar portions of the shell of a diatom.
  8. A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, as in the barberry.
  9. One of the pieces or divisions of bivalve or multivalve shells.
  10. A door; especially, one of a pair of folding doors; a mechanism for opening and closing a passage, and thus regulating or directing the movement through it of gas, liquid, etc.; as, a valve in a steam radiator; in the body, a structure which opens and shuts to allow a fluid to flow through the opening in one direction only; as, the valves of the heart; one of the halves, hinged together so as to open and shut, of the shell of a mollusk of the bivalve class, such as the oyster.
  11. One of the leaves of a folding- door: a cover to an aperture which opens in one direction and not in the other: one of the pieces or divisions which form a shell.
  12. One of the leaves of a folding- door; a lid or cover opening only one way; one of the pieces forming a shell.
  13. An arrangement that permits the flow of a fluid in one direction, and closes against its return.
  14. One of a pair of folding doors.
  15. The leaf of a folding- door; a lid or cover to an aperture, so formed as to open a communication in one direction and close it in the other; one of the pieces into which a pericarp naturally separates when it bursts; one of the divisions of a shell.
  16. Anything that opens over the mouth of a vessel; a cover or lid opening in one direction and shutting in another; in bot., one of the pieces into which a pericarp or fruit separates, when separating naturally.
  17. Any of the various structures which permit flow in one direction, but are capable of closing the tube or vessel and preventing the backward flow; any of the pieces formed by a capsule on dehiscence; the lid- like structure of certain anthers; one of the pieces forming the shell of a Diatom; any of the pieces which form the shell in certain Molluscs, Barnacles, etc.; one of the pieces forming the sheath of the ovipositor in certain Insects.
  18. Valved.
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