The Collaborative International Dictionary of English v.0.48:

Barbarity \Bar*bar"i*ty\, n.; pl. Barbarities. [From
   Barbarous.]
   1. The state or manner of a barbarian; lack of civilization.
      [1913 Webster]

   2. Cruelty; ferociousness; inhumanity.
      [1913 Webster]

            Treating Christians with a barbarity which would
            have shocked the very Moslem.         --Macaulay.
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   3. A barbarous or cruel act.
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   4. Barbarism; impurity of speech. [Obs.] --Swift.
      [1913 Webster]

WordNet (r) 3.0 (2006):

barbarity
    n 1: the quality of being shockingly cruel and inhumane [syn:
         atrocity, atrociousness, barbarity, barbarousness,
         heinousness]
    2: a brutal barbarous savage act [syn: brutality, barbarity,
       barbarism, savagery]