1 a hole in the surface of a road that is formed by traffic and bad weather （路面上因来往车辆或坏天气而形成的）凹坑，小坑，坑洞

2 a deep hole in rock that is formed by water over thousands of years and often leads to underground rooms (caves) 壶穴，锅穴，瓯穴（岩石几千年来被水侵蚀而形成的深洞，多通至地下洞穴）