1) Brutality 2) Coldness 3) Cruelty 4) Hardness 5) Heartlessness 6) Insensibility 7) Insensitiveness 8) Insensitivity 9) Lack of feeling 10) Lack of sympathy 11) Mercilessness 12) Pitilessness 13) Unfeelingness 1) Cruelty 2) Nastiness 3) Unfeelingness 4) Unkindness 
callousness 1. Having calluses; toughened: 'He had callousness on the skin of his elbow.' 2. This calloiusness has nothing to do with the descriptive term meaning, 'emotionally hardened; unfeeling' and the two usages should not be used for the same application.
a lack of sympathy or regard for others