1) Atrociousness 2) Atrocity 3) Barbarity 4) Barbarousness 5) Inhumaneness 6) Inhumanity 
heinous, heinously, heinousness 1. Shockingly brutal or cruel; hateful; odious. 2. Grossly wicked or reprehensible; abominable: 'The shooter of the students committed a heinous crime.' 3. Etymology: from Old French haineus; from French haineux, from haine, 'hatred'; and hair, 'to hate'.