Definition of soundtracks:
(n) :
The sound (especially the music) component of a movie, video game, etc.
(n) :
A recording of such music for sale.
(n) :
A narrow strip running down a movie film that carries the recorded sound in synchronization with the pictures.
(n) :
A background sound that is part of a larger event.
(v) :
(transitive) To provide, or to act as, the sound or music component of a film.