pitilessness       
noun [ U ] uk/ˈpɪt.i.ləs.nəs/ us/ˈpɪt̬.i.ləs.nəs/
 残酷无情
the quality of being cruel and showing no sympathy for others
  He was sacked for cruelty by a regime that prided itself on its pitilessness.  他因残忍行为而被一个以无情为自豪的政权解雇。 
 The secret police believed in torture and pitilessness.  秘密警察信奉酷刑和无情。 
 See: pitiless
 - More examples
 - This scene is one of appalling carnage, torment, and pitilessness.
 - They treated their own people with a pitilessness other nations reserved for their enemies.
 - The whole story of pitilessness and tragedy is revealing in a number of unexpected ways.