The Collaborative International Dictionary of English v.0.48:

Brigand \Brig"and\ (br[i^]g"and), n. [F. brigand, OF. brigant
   light-armed soldier, fr. LL. brigans light-armed soldier (cf.
   It. brigante.) fr. brigare to strive, contend, fr. briga
   quarrel; prob. of German origin, and akin to E. break; cf.
   Goth. brikan to break, brakja strife. Cf. Brigue.]
   1. A light-armed, irregular foot soldier. [Obs.]
      [1913 Webster]

   2. A lawless fellow who lives by plunder; one of a band of
      robbers; especially, one of a gang living in mountain
      retreats; a highwayman; a freebooter.
      [1913 Webster]

            Giving them not a little the air of brigands or
            banditti.                             --Jeffery.
      [1913 Webster]

WordNet (r) 3.0 (2006):

brigand
    n 1: an armed thief who is (usually) a member of a band [syn:
         bandit, brigand]