What is "to take the bull by the horns"

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. (Zo["o]l.) 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.

   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.
   --Ps. xxii. 12.

3. (Astron.)

   1. Taurus, the second of the twelve signs of the zodiac.

   2. 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. 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.

   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.