The Collaborative International Dictionary of English v.0.48:

Plunder \Plun"der\, v. t. [imp. & p. p. Plundered; p. pr. &
   vb. n. Plundering.] [G. pl["u]ndern to plunder, plunder
   frippery, baggage.]
   1. To take the goods of by force, or without right; to
      pillage; to spoil; to sack; to strip; to rob; as, to
      plunder travelers.
      [1913 Webster]

            Nebuchadnezzar plunders the temple of God. --South.
      [1913 Webster]

   2. To take by pillage; to appropriate forcibly; as, the enemy
      plundered all the goods they found.
      [1913 Webster]

   Syn: To pillage; despoil; sack; rifle; strip; rob.
        [1913 Webster]

WordNet (r) 3.0 (2006):

plundering
    adj 1: given to taking by force what is desired
    n 1: the act of stealing valuable things from a place; "the
         plundering of the Parthenon"; "his plundering of the great
         authors" [syn: plundering, pillage, pillaging]

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "plundering":
   banditry, brigandage, brigandism, depredation, despoiling,
   despoilment, despoliation, direption, foraging, foray, freebooting,
   looting, marauding, pillage, pillaging, plunder, plunderous,
   predacious, predatory, raid, raiding, ransacking, rape, rapine,
   ravage, ravagement, ravaging, ravishment, razzia, reiving, rifling,
   sack, sacking, spoiling, spoliation, spoliatory