Mogul
A bump of compacted snow formed when many skiers carve turns in the same place on a steep slope, leaving mounds and troughs.
Moguls form naturally on ungroomed steep pistes as skiers push snow out of their turns. Over a day the piled snow hardens into bumps with narrow troughs between them, creating the characteristic bump field.
Skiing moguls well is a core advanced technique - absorbing each bump with the legs, turning in the troughs, and keeping the upper body quiet and facing downhill.