| 1. | a large-scale, atmospheric wind-and-pressure system characterized by low pressure at its center and by circular wind motion, counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere. Compare anticyclone, extratropical cyclone, tropical cyclone. |
| 2. | (not in technical use) tornado. |
| 3. | Also called cyclone collector, cyclone separator. Machinery. a device for removing small or powdered solids from air, water, or other gases or liquids by centrifugal force. |

Any circular wind motion. A region of low atmospheric pressure. Also, a tropical storm.
Note: Cyclones can be a few feet across (“dust devils”) or can be major storm systems such as hurricanes, tornadoes, and typhoons.
Note: These winds move counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. (See Coriolis effect.)