The Collaborative International Dictionary of English v.0.48:

brutalise \brutalise\ v. t.
   1. to treat brutally.

   Syn: brutalize.
        [WordNet 1.5]

   2. to cause to become like a brute; as, life in the
      concentration camp had brutalised him.

   Syn: brutalize.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

brutalise \brutalise\ v. i.
   to become brutal.

   Syn: brutalize.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

brutalise
    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]