Atrocious killing is a phrase that refers to an act of violence or murder that is particularly heinous or shocking in some way. Some synonyms for this phrase include: brutal slaying, savage murder, barbarous killing, monstrous homicide, cruel slaughter, and merciless assassination. Each of these words carries a strong connotation of violence and brutality, and all suggest a sense of horror and shock at the act being described. While these synonyms may be useful for conveying the severity of a particular crime, they also serve as a reminder of the darkness and tragedy that can exist in the world.