Definitions
1.nounA collection point for mail intended for onward delivery, a secure box or receptacle for this purpose.
2.nounA delivery point for mail, a box, compartment or slot for this purpose.
3.nounA hidden container that holds a logbook and rubber stamp, found by following clues.
4.verbTo 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.
5.verbTo hunt for letterboxes (containers with logbook and rubber stamp) by following clues.
6.adjectiveTransferred to home video formats while preserving the original aspect ratio, having black bars above and below the picture area.