The Collaborative International Dictionary of English v.0.48:

Bull \Bull\, n. [OE. bule, bul, bole; akin to D. bul, G. bulle,
   Icel. boli, Lith. bullus, Lett. bollis, Russ. vol'; prob. fr.
   the root of AS. bellan, E. bellow.]
   1. (Zool.) The male of any species of cattle (Bovid[ae]);
      hence, the male of any large quadruped, as the elephant;
      also, the male of the whale.
      [1913 Webster]

   Note: The wild bull of the Old Testament is thought to be the
         oryx, a large species of antelope.
         [1913 Webster]

   2. One who, or that which, resembles a bull in character or
      action. --Ps. xxii. 12.
      [1913 Webster]

   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.
          [1913 Webster]

                At last from Aries rolls the bounteous sun,
                And the bright Bull receives him. --Thomson.
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   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.
      [1913 Webster]

   5. a ludicrously false statement; nonsense. Also used as an
      expletive. [vulgar]

   Syn: bullshit, Irish bull, horseshit, shit, crap, crapola,
        bunk, bunkum, buncombe, guff, nonsense, rot, tommyrot,
        balderdash, hogwash, dogshit.
        [WordNet 1.5]

   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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Bovidae
    n 1: true antelopes; cattle; oxen; sheep; goats [syn: Bovidae,
         family Bovidae]