Definition of "soundtrack"

soundtrack

noun
plural soundtracks
1. A narrow strip running down a movie film that carries the recorded sound in synchronization with the pictures.
2. The sound (especially the music) component of a movie, video game, etc.
3. A recording of such music for sale.
4. Background sounds that are part of a bigger event.
  Quotations
  There was a startling lack of creativity and if Van Gaal had listened closely he would have made out the mocking chants from the away end, as the visiting fans embarked on the repertoire of songs that formed the soundtrack to David Moyes’s time in the job.
  August 16 2014, Daniel Taylor, "Swansea upstage Manchester United in Louis van Gaal’s Premier League bow," guardian.co.uk
verb
third-person singular simple present soundtracks, present participle soundtracking, simple past and past participle soundtracked
1. To provide, or to act as the sound or music component of a film
  Quotations
  The world, in turn, watched, clicked, cried, danced, sang along, swooned, caravanned to stadiums and movie theaters, let her work soundtrack their lives.
  2023 December 6, Sam Lansky, “Person of Year 2023 : Taylor Swift”, in Time‎