Webster 1913 Edition
[Gr.[GREEK][GREEK][GREEK][GREEK][GREEK] moving in a circle, p. pr. of [GREEK][GREEK][GREEK][GREEK][GREEK], fr.
A violent storm, often of vast extent, characterized by high winds rotating about a calm center of low atmospheric pressure. This center moves onward, often with a velocity of twenty or thirty miles an hour.
☞ The atmospheric disturbance usually accompanying a cyclone, marked by an onward moving area of high pressure, is called an anticyclone.