a. An atmospheric system characterized by the rapid inward circulation of air masses about a low-pressure center, usually accompanied by stormy, often destructive weather. Cyclones circulate counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
b. A violent tropical storm, especially one originating in the southwestern Pacific Ocean or Indian Ocean.
2. A violent rotating windstorm, especially a tornado.
3. Any of various devices using centrifugal force to separate materials.
[From Greek kuklōn, present participle of kukloun, to rotate, from kuklos, circle; see kwel-1 in the Appendix of Indo-European roots.]
cy·clonic (-klŏnĭk), cy·cloni·cal adj.
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