swallow hole

美 [ˈswɑːloʊ hoʊl]英 [ˈswɒləʊ həʊl]
  • 网络落水洞;燕子洞;吞口
swallow holeswallow hole

noun

1
a depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof
Synonym: sinkhole sink

数据来源:WordNet