bugle vs letterbox

bugle

noun
  • Anything shaped like a bugle, round or conical and having a bell on one end. 

  • A simple brass instrument consisting of a horn with no valves, playing only pitches in its harmonic series 

  • A sort of wild ox; a buffalo. 

  • A plant in the family Lamiaceae grown as a ground cover Ajuga reptans, and other plants in the genus Ajuga. 

  • A tubular glass or plastic bead sewn onto clothes as a decorative trim 

  • A horn used by hunters. 

  • The sound of something that bugles. 

verb
  • To announce, sing, or cry in the manner of a musical bugle. 

letterbox

noun
  • A rectangular hole or slot. 

  • A hidden container that holds a logbook and rubber stamp, found by following clues as a form of recreation. 

  • A delivery point for mail, a box, compartment or slot for this purpose. 

  • A collection point for mail intended for onward delivery, a secure box or receptacle for this purpose. 

verb
  • To transfer a widescreen motion picture to home video formats while preserving the original aspect ratio, with the placing of black bars above and below the picture area. 

  • To hunt for letterboxes (containers with logbook and rubber stamp) by following clues. 

adj
  • Transferred to home video formats while preserving the original aspect ratio, having black bars above and below the picture area. 

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