I am just sure there must be industry jargon for this, but anyway I will define it.
A recording (like a CD) where the low-volume parts and the high-volume parts are recorded with such a level difference that there is no comfortable volume setting.

Basically, if your stereo is set so that you can appreciate the low-level sections (like a sottovoce), when the high-level section comes in your amplifier overloads and the neighbours call the police.

My prime example of that is Amarok.