The Collaborative International Dictionary of English v.0.48:

Busk \Busk\ (b[u^]sk), n. [F. busc, perh. fr. the hypothetical
   older form of E. bois wood, because the first busks were made
   of wood. See Bush, and cf. OF. busche, F. b[^u]che, a piece
   or log of wood, fr. the same root.]
   A thin, elastic strip of metal, whalebone, wood, or other
   material, worn in the front of a corset.
   [1913 Webster]

         Her long slit sleeves, stiff busk, puff verdingall,
         Is all that makes her thus angelical.    --Marston.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Busk \Busk\ (b[u^]sk), n.
   Among the Creek Indians, a feast of first fruits celebrated
   when the corn is ripe enough to be eaten. The feast usually
   continues four days. On the first day the new fire is
   lighted, by friction of wood, and distributed to the various
   households, an offering of green corn, including an ear
   brought from each of the four quarters or directions, is
   consumed, and medicine is brewed from snakeroot. On the
   second and third days the men physic with the medicine, the
   women bathe, the two sexes are taboo to one another, and all
   fast. On the fourth day there are feasting, dancing, and
   games.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Busk \Busk\, v. t. & i. [imp. & p. p. Busked (b[u^]skt).] [OE.
   busken, fr. Icel. b[=u]ask to make one's self ready,
   rexlexive of b[=u]a to prepare, dwell. Cf. 8th Bound.]
   1. To prepare; to make ready; to array; to dress. [Scot. &
      Old Eng.]
      [1913 Webster]

            Busk you, busk you, my bonny, bonny bride.
                                                  --Hamilton.
      [1913 Webster]

   2. To go; to direct one's course. [Obs.]
      [1913 Webster]

            Ye might have busked you to Huntly banks. --Skelton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

busk
    v 1: play music in a public place and solicit money for it;
         "three young men were busking in the plaza"