1. An area or a region distinguished from adjacent parts by a distinctive feature or characteristic.
2. 1. 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.
   2. A similar division on any other planet.
   3. Mathematics. A portion of a sphere bounded by the intersections of two parallel planes with the sphere.
3. Ecology. An area characterized by distinct physical conditions and populated by communities of certain kinds of organisms.
4. Anatomy. A ringlike or cylindrical growth or structure.
5. Geology. A region or stratum distinguished by composition or content.
6. 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: a residential zone.
7. An area of a given radius within which a uniform rate is charged, as for transportation or shipping.
8. Computer Science.
   1. A region on a punch card or on magnetic tape in which nondigital information is recorded.
   2. A section of storage to be used for a particular purpose.
9. Archaic. A belt or girdle.

1. To divide into zones.
2. To designate or mark off into zones.
3. To surround or encircle with or as if with a belt or girdle.

1. Of, relating to, associated with, or divided into zones; zonal.
2. Sports. Of, relating to, or being a system of defense, especially in basketball and football, in which each defender guards a predetermined part of the playing area rather than an individual player.

zone out Informal.

1. To lose concentration or become inattentive.

in the zone

1. InformalIn a state of focused attention or energy so that one's performance is enhanced:a goalie who was in the zone throughout the playoffs. In a state of focused attention or energy so that one's performance is enhanced: a goalie who was in the zone throughout the playoffs.

[Middle English, one of the encircling regions of the earth, from Latin zōna, girdle, celestial zone, from Greek zōnē.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.