noun.
The term introduced into meteorology by Piddington, in 1840, as a general name for the class of extensive storms at sea that were at that time supposed to be characterized by the revolution of air in circles about a calm center.
noun.
Any atmospheric movement, gentle or rapid, general or local, on land or at sea, in which the wind blows spirally around and in toward a center.
noun.
Popularly, a tornado (such as occur in the Western States), or any destructive storm. See tornado, waterspout, and whirlwind.