massacre vs megadeath

massacre

noun
  • 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. 

  • St. Bartholomew's Day Massacre 

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

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.) 

megadeath

noun
  • One million deaths, especially as a unit of measure in reference to nuclear warfare. 

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