Definition of: cyclone

(sī′klōn) noun
1. Meteorol. A system of winds circulating about a center of relatively low barometric pressure, and, at the earth's surface, advancing with clockwise rotation in the southern hemisphere, counterclockwise in the northern.
2. Loosely, any violent and destructive whirling windstorm. [<Gk. kyklōn, ppr. of kykloein move in a circle <kyklos]
—cy·clo·nal (sī·klō′nəl), cy·clon·ic (sī·klon′ik) or ·i·cal adjective
—cy·clon′i·cal·ly adverb