The Collaborative International Dictionary of English v.0.48:

Brutalize \Bru"tal*ize\, v. t. [imp. & p. p. Brutalized; p.
   pr. & vb. n. Brutalizing.] [Cf. F. brutaliser.]
   To make brutal; beasty; unfeeling; or inhuman.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Brutalize \Bru"tal*ize\, v. i.
   To become brutal, inhuman, barbarous, or coarse and beasty.
   [R.]
   [1913 Webster]

         He mixed . . . with his countrymen, brutalized with
         them in their habits and manners.        --Addison.
   [1913 Webster]

WordNet (r) 3.0 (2006):

brutalize
    v 1: treat brutally [syn: brutalize, brutalise]
    2: make brutal, unfeeling, or inhuman; "Life in the camps had
       brutalized him" [syn: brutalize, brutalise, animalize,
       animalise]
    3: become brutal or insensitive and unfeeling [syn: brutalize,
       brutalise, animalize, animalise]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "brutalize":
   assault, attack, barbarize, bastardize, batter, burn, butcher,
   callous, carry on, case harden, corrupt, debauch, demoralize,
   deprave, destroy, go on, hammer, harden, indurate, inure,
   lay waste, loot, maul, mug, ossify, pervert, pillage, rage, ramp,
   rampage, rant, rape, rave, riot, roar, ruin, sack, savage,
   slaughter, sow chaos, steel, storm, tear, tear around, terrorize,
   vandalize, violate, vitiate, warp, wreck