n. A cavity more or less nearly cylindrical in form, and from a few inches to several feet in depth and diameter, made by an eddying current of water, which causes a stone or a collection of detrital material to revolve and thus wear away the rock with which it is in contact.To produce in (a solid rock mass) a hole by the action of stones and silt whirled around in an eddy of water. The effect of such action is to produce a deep cylindrical hole, called a well, or a hollowed cavity, called a pot-hole, or, in rare cases, a very large and deep, more or less cylindrical and hollowed cavern, called a giants' kettle or cauldron.