aggression vs palliation

aggression

noun
  • Hostile or destructive behavior or actions. 

  • The practice or habit of launching attacks. 

  • The act of initiating hostilities or invasion. 

palliation

noun
  • Extenuation; mitigation. 

  • The alleviation of a disease's symptoms without a cure; temporary relief. 

How often have the words aggression and palliation occurred in a corpus of books? (source: Google Ngram Viewer )