zone

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An area or a region distinguished from adjacent parts by a distinctive feature or characteristic.
• noun A section of an area or territory established for a specific purpose, as a section of a city restricted to a particular type of building, enterprise, or activity.
• noun An area of a given radius within which a uniform rate is charged, as for transportation or shipping.
• noun Any of the five regions of the surface of the earth that are loosely divided according to prevailing climate and latitude, including the Torrid Zone, the North and South Temperate Zones, and the North and South Frigid Zones.
• noun A similar division on any other planet.
• noun Mathematics A portion of a sphere bounded by the intersections of two parallel planes with the sphere.
• noun Ecology An area characterized by distinct physical conditions and supporting a particular type of flora and fauna.
• noun Anatomy A ringlike or cylindrical growth or structure.
• noun Geology A region or stratum distinguished by composition or content.
• noun Sports A zone defense.
• noun Archaic A belt or girdle.
• transitive verb To divide or designate into zones.
• transitive verb To surround or encircle.
• idiom Informal (in the zone) In a state of focused attention or energy so that one's performance is enhanced.

from The Century Dictionary.

• To encircle with or as if with a zone; bring within a zone, or divide into zones or belts, in any sense.
• To be formed into zones.
• noun A portion of the surface of a sphere cut off by one plane.
• noun A belt on the surface of the earth or of the celestial sphere included between two parallels to the equator.
• noun In phytogeography, a vegetation ring or belt: referring more directly to the plant-content itself or to the areas marked by œcological difference.
• noun One of the different levels of a shaft-furnace, characterized according to the reaction which takes place in it: as, the zone of fusion, reduction-zone, etc.
• noun Transition climate, in which the variation is greater than 15° C. and less than 20° C.
• noun Land climate, in which the variation is greater than 20° C. and less than 40° C.
• noun Extreme continental climate in which the variations are greater than 40° C. Koeppen's climatic zones are arbitrary divisions based upon temperature considerations as follows: A tropical zone having an average temperature of over 68° F.
• noun A subtropical zone which has the same temperature during 4 to 11 months.
• noun A constant temperate zone with a temperature between 50 and 68° F.
• noun A hot summer temperate zone which has an average temperature that sometimes falls below 50° F.
• noun A moderate summer and cold winter temperate zone with a temperature between 50 and 68° F.
• noun A cold zone with a prevailing temperature below 50° F.
• noun A polar zone with an average temperature always below 50° F. Wojeikoff's climatic zones are distinguished according to the quantity and character of the rainfall. Twelve climatic regions are shown upon his maps as follows: A zone of ocean trades with very rare rainfalls.
• noun A region of equatorial rains, including the zone of calms.
• noun A region of rain which prevails throughout the year.
• noun A subtropical zone with rainless summers.
• noun A zone of the fall and winter rains of middle latitudes.
• noun The zone of summer rainfall of middle latitudes.
• noun The zone of equal distribution of rain throughout all seasons.
• noun A polar region with light snows in winter.
• noun Deserts and semi-deserts with an annual precipitation less than 250 mm. (10 in.).
• noun (10) The region of the Australian monsoons.
• noun (11) The region of the Asiatic monsoons.
• noun (12) The region of the African monsoons. Climatic zones in altitude correspond to climatic zones in latitude and are marked by the retardation of the dates of the development of vegetation; this retardation amounts to about ten days for every 300 meters of increase in altitude in the Alps, or four days for 800 meters in France.
• noun that their southward distribution is governed by the mean temperature of a brief period covering the hottest part of the year. Upon this basis Merriam has made the following transcontinental divisions for North America:
• noun Tropical region (not subdivided latitudinally).
• noun Upon the basis of humidity, the transition zone is subdivided into the Alleghanian area, the arid transition area, and the Pacific Coast transition area; the Upper Austral into the Carolinian and Upper Sonoran areas; and the Lower Austral into the Austroriparian (Louisianian) and the Lower Sonoran areas. See phrases under area.
• noun A bed or series of beds in any geological formation characterized by certain fossils or groups of fossils: nearly equivalent in meaning to life-horizon.
• noun A girdle or belt worn as an article of dress.
• noun A belt or band round anything, as a stripe of different color or substance round an object; figuratively, any circumscribing or surrounding line, real or imaginary; a circuitous line, path, or course; an inclosing circle.