The Collaborative International Dictionary of English v.0.48:
Prey \Prey\, v. i. [imp. & p. p. Preyed; p. pr. & vb. n.
Preying.] [OF. preier, preer, L. praedari, fr. praeda. See
To take booty; to gather spoil; to ravage; to take food by
More pity that the eagle should be mewed,
While kites and buzzards prey at liberty. --Shak.
To prey on or To prey upon.
(a) To take prey from; to despoil; to pillage; to rob.
(b) To seize as prey; to take for food by violence; to seize
and devour. --Shak.
(c) To wear away gradually; to cause to waste or pine away;
as, the trouble preyed upon his mind. --Addison.