Real Dictionary

Muzak
uncountable noun: Muzak is recorded music that is played as background music in shops or restaurants.

Muzak in American English
a system of transmitting recorded background music by telephone line or radio to restaurants, stores, factories, etc.
the music so transmitted, variously regarded as unobtrusive but pervasive, bland and monotonous, etc.
noun: recorded background music transmitted by radio, telephone, or satellite to built-in sets in offices, restaurants, waiting rooms, etc.

Muzak in British English
noun: recorded light music played in shops, restaurants, factories, etc, to entertain, increase sales or production, etc