The Collaborative International Dictionary of English v.0.48:

Depredate \Dep"re*date\, v. t. [imp. & p. p. Depredated; p.
   pr. & vb. n. Depredating.] [L. depraedatus, p. p. of
   depraedari to plunder; de- + praedari to plunder, praeda
   plunder, prey. See Prey.]
   To subject to plunder and pillage; to despoil; to lay waste;
   to prey upon.
   [1913 Webster]

         It makes the substance of the body . . . less apt to be
         consumed and depredated by the spirits.  --Bacon.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Depredate \Dep"re*date\, v. i.
   To take plunder or prey; to commit waste; as, the troops
   depredated on the country.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "depredate":
   bring to ruin, condemn, confound, consume, damn, deal destruction,
   decimate, desecrate, desolate, despoil, destroy, devastate, devour,
   dissolve, engorge, fleece, forage, foray, freeboot, gobble,
   gobble up, gut, gut with fire, havoc, incinerate, lay in ruins,
   lay waste, loot, maraud, pillage, plunder, prey on, raid, ransack,
   ravage, raven, ravish, reive, rifle, ruin, ruinate, sack,
   shipwreck, spoil, spoliate, swallow up, sweep, throw into disorder,
   unleash destruction, unleash the hurricane, upheave, vandalize,
   vaporize, waste, wrack, wreak havoc, wreck