back matter vs tailpiece

back matter

noun
  • The parts of a book that appear after the main portion of the body text, including the afterword, index and bibliography; the end matter. 

tailpiece

noun
  • An appendage or appendix. 

  • An element, often triangular, to which the strings of a violin, guitar, etc. are attached at the lower end of an instrument. 

  • A short joist between a header and a wall. 

  • The part of a telescope containing the adjusting device for the eyepiece, etc. 

  • The part of a lock that transmits motion from the hub to the latch bolt. 

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