not to be confused with ripping farts...
it's simply packaging the cd into some sort of format so it can be traded/recreated.. (ie you 'rip' a cd into mp3 files or a game into a bin/cue)
a more precise definition would involve actually removing/repackaging to make something smaller, yet still playable/working.. ie; they take out audio tracks or downsize movies on DC/PS2 games to make 'em fit on a cd, or take just enough of the data on a game cd to play it in the pc warez scene (ie; no audio/movies - take a 650 meg cd and just extract the 40 megs that you actually need to play the game)
EG; if you take a sega cd and use cdr-win to make a bin/cue of the entire disc, you "IMAGED" the disc. if you extract the audio tracks and compress em with mp3 (or maybe even remove 'em entirely), you "RIPPED" it..