Source : Webster's Revised Unabridged Dictionary (1913)

Freebooter \Free"boot`er\, n. [D. vrijbuiter, fr. vrijbuiten to
   plunder; vrij free + buit booty, akin to E. booty. See
   {Free}, and {Booty}, and cf. {Filibuster}.]
   One who plunders or pillages without the authority of
   national warfare; a member of a predatory band; a pillager; a
   buccaneer; a sea robber. --Bacon.

Source : WordNet®

freebooter
     n : someone who takes spoils or plunder (as in war) [syn: {plunderer},
          {pillager}, {looter}, {spoiler}, {despoiler}, {raider}]