euphemism vs litotes

euphemism

noun
  • The use of a word or phrase to replace another with one that is considered less offensive, blunt or vulgar than the word or phrase which it replaces. 

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

litotes

noun
  • An ironic figure of speech whereby something is stated by denying its opposite, particularly the negation of a negative quality to say something positive. 

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