A hurricane is a strong tropical cyclone: a rapidly rotating storm with a low-pressure center, a closed low-level circulation, and maximum sustained winds of at least 74 mph (119 km/h). The name is used for storms in the Atlantic and northeastern Pacific; the same storms are called typhoons in the northwestern Pacific.
Its key features are a calm, often clear eye at the center, a ring of the most violent winds and heaviest rain called the eyewall, and spiral rainbands around it. Hurricanes form over warm tropical ocean water, roughly 26.5 C (80 F) or warmer, rotate counterclockwise in the Northern Hemisphere, and weaken once they move over land or cooler water.
Source: Tropical cyclone, Wikipedia
Image: Hurricane Florence from the International Space Station, NASA, public domain, via Wikimedia Commons.