addendum vs postlude

addendum

noun
  • A postscript. 

  • The height by which the tooth of a gear projects beyond (outside for external, or inside for internal) the standard pitch circle or pitch line. 

  • Something to be added; especially text added as an appendix or supplement to a document. 

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 addendum and postlude occurred in a corpus of books? (source: Google Ngram Viewer )