n.
Pronunciation: ' si ŋ k- ˌ h ō l
Function: noun
Date: 15th century
1 : a hollow place or depression in which drainage collects
2 : a hollow in a limestone region that communicates with a cavern or passage
3 : SINK 2
4 : something (as an unprofitable investment) that steadily drains money or resources <a financial sinkhole >