The Collaborative International Dictionary of English v.0.48:
Barbarousness \Bar"ba*rous*ness\, n. The quality or state of being barbarous; barbarity; barbarism. [1913 Webster]WordNet (r) 3.0 (2006):
barbarousness n 1: the quality of being shockingly cruel and inhumane [syn: atrocity, atrociousness, barbarity, barbarousness, heinousness]