defamation vs dysphemism

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. 

dysphemism

noun
  • The use of a word or phrase carrying negative connotations or imagery (especially one that is derogatory, offensive or vulgar) to replace a (more) neutral original. 

  • A word or phrase that is used to replace another in this way. 

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