felicity vs incentive

felicity

noun
  • Something that is either a source of happiness or particularly apt. 

  • An apt and pleasing style in speech, writing, etc.; (countable) an apt and pleasing choice of words. 

  • Happiness; (countable) an instance of this. 

  • Reproduction of a sign with fidelity. 

  • Good luck; success; (countable) An instance of unexpected good luck; a stroke of luck; also, a lucky characteristic. 

incentive

noun
  • Something that motivates, rouses, or encourages. 

  • A bonus or reward, often monetary, to work harder. 

adj
  • Inciting; encouraging or moving; rousing to action; stimulating. 

  • Serving to kindle or set on fire. 

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