Valve n.
 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
 Repassed.   --Pope.
    Heavily closed, . . . the valves of the barn doors.   --Longfellow.
 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.
 4. Bot. (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 diatom. (c) A small portion of certain anthers, which opens like a trapdoor to allow the pollen to escape, as in the barberry.
 5. Zool. One of the pieces or divisions of bivalve or multivalve shells.
 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.
 Equilibrium valve. (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 it.
 Valve yoke Mach., a strap embracing a slide valve and connecting it to the valve stem.

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 Ball n.
 1. Any round or roundish body or mass; a sphere or globe; as, a ball of twine; a ball of snow.
 2. A spherical body of any substance or size used to play with, as by throwing, knocking, kicking, etc.
 3. A general name for games in which a ball is thrown, kicked, or knocked. See Baseball, and Football.
 4. Any solid spherical, cylindrical, or conical projectile of lead or iron, to be discharged from a firearm; as, a cannon ball; a rifle ball; -- often used collectively; as, powder and ball. Spherical balls for the smaller firearms are commonly called bullets.
 5. Pyrotechnics & Mil. A flaming, roundish body shot into the air; a case filled with combustibles intended to burst and give light or set fire, or to produce smoke or stench; as, a fire ball; a stink ball.
 6. Print. A leather-covered cushion, fastened to a handle called a ballstock; -- formerly used by printers for inking the form, but now superseded by the roller.
 7. A roundish protuberant portion of some part of the body; as, the ball of the thumb; the ball of the foot.
 8. Far. A large pill, a form in which medicine is commonly given to horses; a bolus.
 9. The globe or earth.
    Move round the dark terrestrial ball.   --Addison.
 10. Baseball A pitched ball, not struck at by the batter, which fails to pass over the home plate at a height not greater than the batter's shoulder nor less than his knee (i.e. it is outside the strike zone).  If the pitcher pitches four balls before three strikes are called, the batter advances to first base, and the action of pitching four balls is called a walk.
 Ball and socket joint, a joint in which a ball moves within a socket, so as to admit of motion in every direction within certain limits.
 Ball bearings, a mechanical device for lessening the friction of axle bearings by means of small loose metal balls.
 Ball cartridge, a cartridge containing a ball, as distinguished from a blank cartridge, containing only powder.
 Ball cock, a faucet or valve which is opened or closed by the fall or rise of a ball floating in water at the end of a lever.
 Ball gudgeon, a pivot of a spherical form, which permits lateral deflection of the arbor or shaft, while retaining the pivot in its socket. --Knight.
 Ball lever, the lever used in a ball cock.
 Ball of the eye, the eye itself, as distinguished from its lids and socket; -- formerly, the pupil of the eye.
 Ball valve Mach., a contrivance by which a ball, placed in a circular cup with a hole in its bottom, operates as a valve.
 Ball vein Mining, a sort of iron ore, found in loose masses of a globular form, containing sparkling particles.
 Three balls, or Three golden balls, a pawnbroker's sign or shop.
 on the ball alert; competent and knowledgeable.
 to carry the ball to carry on the task; to assume the responsibility.
 to drop the ball to fail to perform as expected; to fail to live up to a responsibility.
 Syn: -- See Globe.


 ball valve
      n : any valve that checks flow by the seating of a ball