Zone

—One of the five great divisions of the earth, with respect to latitude and temperature. They are the torrid zone, extending from tropic to tropic 46° 56’, or 23° 28’, on each side of the equator; two temperate or variable zones, situated between the tropics and polar circles; and two frigid zones situated between the polar circles and the poles. 2. In mathematics, the portion of the surface of a sphere included between two parallel planes.