col       
noun [ C ]  geology specialized uk/kɒl/ us/kɑːl/
 山口,山坳
the lowest point of a high edge between two mountains, usually where you can pass between them
  From the col there is a wonderful view back down over the ski village.  从山口往可以看到滑雪村美丽的景色。 
 - More examples
 - The great cols are ways of getting through the mountains.
 - The riders of the Tour de France will climb through the Vosges mountains, each of the cols harder than the one before.
 - This is the col between Tryfan and Glyder Fach, from where the South Ridge of Tryfan leads to the summit.
 - Finally we crest a col and the hut looms into view.