Backcountry Ski - explained in the PalmerProject-Ski and Snowboard-Lexicon
Backcountry skiing is skiing in a sparsely inhabited rural region over ungroomed and unmarked slopes or pistes. More importantly, the land and the snow pack are not monitored, patrolled, or maintained. Fixed mechanical means of ascent such as ski lifts are typically not present. Backcountry skis are perceived as enjoyable skiing in different, natural and ungroomed snow conditions.