The Collaborative International Dictionary of English v.0.48:

Brisket \Bris"ket\, n. [OE. bruskette, OF. bruschet, F.
   br['e]chet, brichet; prob. of Celtic origin; cf. W. brysced
   the breast of a slain animal, brisket, Corn. vrys breast,
   Armor. brusk, bruched, the front of the chest, Gael. brisgein
   the cartilaginous part of a bone.]
   That part of the breast of an animal which extends from the
   fore legs back beneath the ribs; also applied to the fore
   part of a horse, from the shoulders to the bottom of the
   chest.

   Note: [See Illust. of Beef.]
         [1913 Webster]

WordNet (r) 3.0 (2006):

brisket
    n 1: a cut of meat from the breast or lower chest especially of
         beef