The Collaborative International Dictionary of English v.0.48:
Valve \Valve\, n. [L. valva the leaf, fold, or valve of a door:
cf. F. valve.]
1. A door; especially, one of a pair of folding doors, or one
of the leaves of such a door.
Swift through the valves the visionary fair
Heavily closed, . . . the valves of the barn doors.
2. 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.
Note: A valve may act automatically so as to be opened by the
effort of a fluid to pass in one direction, and closed
by the effort to pass in the other direction, as a
clack valve; or it may be opened or closed by hand or
by mechanism, as a screw valve, or a slide valve.
3. (Anat.) 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.
(a) One of the pieces into which a capsule naturally
separates when it bursts.
(b) One of the two similar portions of the shell of a
(c) A small portion of certain anthers, which opens like a
trapdoor to allow the pollen to escape, as in the
5. (Zool.) One of the pieces or divisions of bivalve or
Air valve, Ball valve, Check valve, etc. See under
Air. Ball, Check, etc.
Double-beat valve, a kind of balance valve usually
consisting of a movable, open-ended, turban-shaped shell
provided with two faces of nearly equal diameters, one
above another, which rest upon two corresponding seats
when the valve is closed.
(a) A balance valve. See under Balance.
(b) A valve for permitting air, steam, water, etc., to
pass into or out of a chamber so as to establish or
maintain equal pressure within and without.
Valve chest (Mach.), a chamber in which a valve works;
especially (Steam Engine), the steam chest; -- called in
England valve box, and valve casing. See Steam
chest, under Steam.
Valve face (Mach.), that part of the surface of a valve
which comes in contact with the valve seat.
Valve gear, or Valve motion (Steam Engine), the system of
parts by which motion is given to the valve or valves for
the distribution of steam in the cylinder. For an
illustration of one form of valve gear, see Link motion.
Valve seat. (Mach.)
(a) The fixed surface on which a valve rests or against
which it presses.
(b) A part or piece on which such a surface is formed.
Valve stem (Mach.), a rod attached to a valve, for moving
Valve yoke (Mach.), a strap embracing a slide valve and
connecting it to the valve stem.