appendix vs postlude

appendix

noun
  • A text added to the end of a book or an article, containing additional information. 

  • Any process, prolongation, or projection. 

  • The vermiform appendix. 

postlude

noun
  • A concluding passage of text or speech; an epilogue or afterword. 

  • The final part of a piece; especially music played (normally on the organ) at the end of a church service. 

verb
  • To form a postlude (to); to end with a postlude. 

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