explanation vs palliation

explanation

noun
  • The act or process of explaining. 

  • Something that explains, makes understandable. 

  • A resolution of disputed points pursuant to discussion; a mutual clarification of disputed points; reconciliation. 

palliation

noun
  • Extenuation; mitigation. 

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

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