apologue vs novelette

apologue

noun
  • A short story with a moral, often involving talking animals or objects; a fable. 

  • The use of fable to persuade the audience. 

novelette

noun
  • A short novel. 

  • A short piece of lyrical music, especially one for the piano. 

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