chamber vs letterbox

chamber

noun
  • Any enclosed space occupying or similar to a room. 

  • One of the bullet-holding compartments in the cylinder of a revolver. 

  • The legislature or division of the legislature itself. 

  • The room used for deliberation by a legislature. 

  • A short piece of ordnance or cannon which stood on its breech without any carriage, formerly used chiefly for celebrations and theatrical cannonades. 

  • The private office of a judge. 

  • One of the two atria or two ventricles of the heart. 

  • The private room of an individual, especially of someone wealthy or noble. 

  • A single law office in a building housing several. 

  • The area holding the ammunition round at the initiation of its discharge. 

  • A bedroom. 

  • An enlarged space in an underground tunnel of a burrowing animal. 

verb
  • To place in a chamber, as a round of ammunition. 

  • To reside in or occupy a chamber or chambers. 

  • To create or modify a gun to be a specific caliber. 

  • To enclose in a room. 

  • To prepare an offensive, defensive, or counteroffensive action by drawing a limb or weapon to a position where it may be charged with kinetic energy. 

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. 

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

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. 

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