any continuous tract or area that differs in some respect, or is distinguished for some purpose, from adjoining tracts or areas, or within which certain distinctive circumstances exist or are established.
Geography. any of five great divisions of the earth's surface, bounded by lines parallel to the equator and named according to the prevailing temperature. Compare North Frigid Zone, North Temperate Zone, South Frigid Zone, South Temperate Zone, Torrid Zone.
Biogeography. an area characterized by a particular set of organisms, whose presence is determined by environmental conditions, as an altitudinal belt on a mountain.
Geology. a horizon.
Geometry. a part of the surface of a sphere included between two parallel planes.