Source : Webster's Revised Unabridged Dictionary (1913)

Ball \Ball\ (b[add]l), n. [OE. bal, balle; akin to OHG. balla,
   palla, G. ball, Icel. b["o]llr, ball; cf. F. balle. Cf. 1st
   {Bale}, n., {Pallmall}.]
   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      inking the form, but now superseded by the roller.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. --White.

   9. The globe or earth. --Pope.

            Move round the dark terrestrial ball. --Addison.

   {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.

   Syn: See {Globe}.

Cock \Cock\, n. [AS. coc; of unknown origin, perh. in imitation
   of the cry of the cock. Cf. {Chicken}.]
   1. The male of birds, particularly of gallinaceous or
      domestic fowls.

   2. A vane in the shape of a cock; a weathercock.

            Drenched our steeples, drowned the cocks! --Shak.

   3. A chief man; a leader or master. [Humorous]

            Sir Andrew is the cock of the club, since he left
            us.                                   --Addison.

   4. The crow of a cock, esp. the first crow in the morning;
      cockcrow. [Obs.]

            He begins at curfew, and walks till the first cock.
                                                  --Shak.

   5. A faucet or valve.

   Note: Jonsons says, ``The handly probably had a cock on the
         top; things that were contrived to turn seem anciently
         to have had that form, whatever was the reason.''
         Skinner says, because it used to be constructed in
         forma crit[ae] galli, i.e., in the form of a cock's
         comb.

   6. The style of gnomon of a dial. --Chambers.

   7. The indicator of a balance. --Johnson.

   8. The bridge piece which affords a bearing for the pivot of
      a balance in a clock or watch. --Knight.

   {Ball cock}. See under {Ball}.

   {Chaparral cock}. See under {Chaparral}.

   {Cock and bull story}, {an extravagant}, boastful story; a
      canard.

   {Cock of the plains} (Zo["o]l.) See {Sage cock}.

   {Cock of the rock} (Zo["o]l.), a South American bird
      ({Rupicola aurantia}) having a beautiful crest.

   {Cock of the walk}, a chief or master; the hero of the hour;
      one who has overcrowed, or got the better of, rivals or
      competitors.

   {Cock of the woods}. See {Capercailzie}.

Source : WordNet®

ball cock
     n : floating ball that controls level in a water tank [syn: {ballcock}]