Taper

Tapered tip and tail.Classic skis have the widest points located as close as possible to the tops of the tip and heel. In deep snow, softer snow or in crust, this causes the skis to bite and cut. Skis for terrain and deep snow usually have these widest points moved closer to the center. Heels and toes then bite less when going out of bends. The skis are also easier to control because the effective edge is significantly shortened. Another advantage of tapers is the increased stability of the skis in a straight line in deep snow. On the contrary, excessively pronounced tapers reduce the stability of skis on hard surfaces, as we rely on a shorter effective edge.

Source: https://snow.cz/clanek/3655-slovnicek-freeridove-lyze