dysphemism vs softening

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. 

softening

noun
  • The process of becoming soft. 

  • The process of making something soft. 

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