allayment vs assuagement

allayment

noun
  • Something that allays; mitigation 

assuagement

noun
  • The action of assuaging; appeasement. 

  • An assuaging medicine or application. 

  • The condition of being assuaged. 

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