lehtri-, lohu- või liua-kujuline, kuni mitmekümne meetrise (harvem üle 100m) läbimõõduga negatiivne pindmise karsti pinnavorm, is a bowl-shaped, funnel-shaped, or vertical-sided depression in the ground caused by karst processes (chemical dissolution of rocks) induced collapse of the surface layer; may vary in size from 1 to 600 m both in diameter and depth. Can be devided: subsidence -, erosional -, mereged sinkholes.