massacre vs race extermination

massacre

verb
  • To win against (an opponent) very decisively. 

  • To perform (a work, such as a musical piece or a play) very poorly. 

  • To kill with great force or brutality. 

  • To kill in considerable numbers where little or no resistance can be made, with indiscriminate violence, without necessity, and contrary to civilized norms. (Often limited to the killing of human beings.) 

noun
  • St. Bartholomew's Day Massacre 

  • Any overwhelming defeat, as in a game or sport. 

  • The killing of a considerable number (usually limited to people) where little or no resistance can be made, with indiscriminate violence, without necessity, and contrary to civilized norms. 

race extermination

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