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]