tailpiece vs uropygium

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. 

uropygium

noun
  • The posterior part of a bird's body from which the tailfeathers grow. 

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