Couloir

Those deep, dark slots in a mountain known as couloirs are often the most obvious routes of ascent.

Source: wiktionary

Looking up the face I could see directly into the Japanese and Hornbein couloirs, an almost direct 9000 feet to the summit.

Source: wiktionary

Ascend a long, easy snow couloir back left to the crest of Cassin Ridge at 17700 feet, where there is a campsite.

Source: wiktionary

2002, American Alpine Club Safety Committee, Alpine Club of Canada Safety Committee, Accidents in North American Mountaineering, Issue 55, page 58, When they approached the couloir shortly before 0300, the snow was firm enough for them to use crampons.

Source: wiktionary