sinkhole
sink·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
Origin
From Middle English sinkehole, sinkeholl, equivalent to sink + hole.
Related words
Broader terms
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). CMU Pronouncing Dictionary. WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.