a hole in the ground, especially in an area of limestone rock, that has been formed naturally, for example by water that has worn away the rock

Rain gradually dissolves the limestone, forming features such as limestone pavements, sinkholes, and caves. 雨水会逐渐溶解石灰岩，形成灰岩喀斯特面、灰岩坑、溶洞等特征。

Compare: abyss (HOLE) canyonchasmcleftcrater nouncrevassedefile noun gorge noun (VALLEY)gulf (AREA) gullyravinerift

a large hole that suddenly appears in the ground when the surface of the ground is no longer supported

A massive sinkhole has opened over old potash mines in the area. 这个地区的老钾矿突然出现了一个巨大的天坑。

A man was missing early Friday after a large sinkhole opened under the bedroom of his house in Florida. 周五早些时候，佛罗里达州一名男子的卧室地面突然出现了一个巨大的天坑，他随后失踪。