Bull n.
  1. Zool. The male of any species of cattle (Bovidæ); hence, the male of any large quadruped, as the elephant; also, the male of the whale.
  Note: ☞ The wild bull of the Old Testament is thought to be the oryx, a large species of antelope.
  2. One who, or that which, resembles a bull in character or action.
  3. Astron. (a) Taurus, the second of the twelve signs of the zodiac. (b) A constellation of the zodiac between Aries and Gemini. It contains the Pleiades.
  At last from Aries rolls the bounteous sun,
  And the bright Bull receives him.   --Thomson.
  4. Stock Exchange One who operates in expectation of a rise in the price of stocks, or in order to effect such a rise. See 4th Bear, n., 5.
  Bull baiting, the practice of baiting bulls, or rendering them furious, as by setting dogs to attack them.
  John Bull, a humorous name for the English, collectively; also, an Englishman.  “Good-looking young John Bull.” --W. D.Howells.
  To take the bull by the horns, to grapple with a difficulty instead of avoiding it.