genteelism vs understatement

genteelism

noun
  • A nicer word used instead of a vulgar or distasteful word 

  • Genteel behaviour. 

understatement

noun
  • An instance of such phrasing or lack of emphasis. 

  • A figure of speech whereby something is made to seem smaller or less important than it actually is, either through phrasing or lack of emphasis, often for ironic effect. 

  • An incomplete disclosure that intentionally withholds relevant information. 

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