let‧ter‧box‧ing /ˈletəˌbɒksɪŋ $ -terˌbɑːks-/ noun [uncountable]
when a film from the cinema is broadcast on television with black bands at the top and bottom of the television screen so that the film will have the same dimensions as it did on a cinema screen

[TahlilGaran] Dictionary of Contemporary English ▲