Any music in a film, video game, or other medium that establishes mood and is not meant to have the audience's focus.
Background-music Sentence Examples
The room, in near total darkness, held a barely audible hum for background music.
The visions were less invasive than those from others, like background music at a department store.
The packed emergency area waiting room held a disreputable collection of weeping women, stoned teenagers and dirty derelicts, all talking at the same time over the background music of a near-constant scream of sirens hauling in more Saturday night victims.
Even the accompanying background music seemed melodramatic to me, sort of over-indulgent, in a way.