An mp3 release that is compiled from different rips or sources. This was
common during the Napster era of file sharing, where you had to download songs individually.
For
example, you download tracks 1-5 from one site, then got disconnected, so you got tracks 6-14 somewhere else. You end up with an album that most likely has inconsistent bitrates and encoding techniques, and could
even be from different releases of the album (remasters, etc).