water-swallow
/ˈwɔːtəˌswɒləʊ/Now rare
noun
An opening or deep cavity in the ground through which a stream or river disappears underground, especially in an area of water-soluble rock formations such as limestone karst.
Origin
Early 19th century; earliest use found in John Farey (1766–1826), geologist and surveyor. From water + swallow.