Is it ensure, insure, or assure?
a small-diameter column of rapidly swirling air in contact with a water surface. Waterspouts are almost always produced by a swiftly growing cumulus cloud. They may assume many shapes and often occur in a series, called a waterspout family, produced by the same upward-moving air current. Waterspouts are closely related to other atmospheric phenomena such as tornadoes, whirlwinds, and fire storms.