We don't have synonyms for letterboxed yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are letterboxes, letterbox and letterboard.
(n) :
A hobby in which participants attempt to locate small boxes containing rubber stamps by following clues.
(n) :
(film) The practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio.
(n) :
A hobby in which participants attempt to locate small boxes containing rubber stamps by following clues.
(n) :
(film) The practice of transferring film shot in a widescreen aspect ratio to standard-width video formats while preserving the film's original aspect ratio.