defamation vs nastygram

defamation

noun
  • The act of injuring another person's reputation by any slanderous communication, written or oral; the wrong of maliciously injuring the good name of another. 

nastygram

noun
  • A written communication containing unpleasant material, especially one that criticizes, insults, or intimidates the recipient. 

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