Q. What does "acidized" mean when referring to audio tracks?
A. Acidized is a term used for loops which have tempo and pitch data attached to the file. This is how the program "Acid" reads the file and is able to mix different loops of different tempos to sync in the program. They can be used in any program, other programs generally do not read the "acidized" part so it just gets imported as a standard WAV file. In that case you have to adjust tempos yourself to match any particular target tempo, by time-stretching (or time-compressing) the track.