Source : Webster's Revised Unabridged Dictionary (1913)

Tailpiece \Tail"piece`\, n.
   1. (Locks) A piece for transmitting motion from the hub of a
      lock to the latch bolt.

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

Tailpiece \Tail"piece`\, n.
   1. A piece at the end; an appendage.

   2. (Arch.) One of the timbers which tail into a header, in
      floor framing. See Illust. of {Header}.

   3. (Print.) An ornament placed at the bottom of a short page
      to fill up the space, or at the end of a book. --Savage.

   4. A piece of ebony or other material attached to the lower
      end of a violin or similar instrument, to which the
      strings are fastened.

Source : WordNet®

tailpiece
     n : appendage added to extend the length of something