/ree"jeuhn/ , n.
1. an extensive, continuous part of a surface, space, or body: a region of the earth.
2. Usually, regions . the vast or indefinite entirety of a space or area, or something compared to one: the regions of the firmament; the regions of the mind.
3. a part of the earth's surface (land or sea) of considerable and usually indefinite extent: a tropical region.
4. a district without respect to boundaries or extent: a charming region in Connecticut.
5. a part or division of the universe, as the heavens: a galactic region.
6. a large indefinite area or range of something specified; sphere: a region of authority.
7. an area of interest, activity, pursuit, etc.; field: studies in the region of logic.
8. an administrative division of a city or territory.
9. Zoogeog. a major faunal area of the earth's surface, sometimes one regarded as a division of a larger area.
10. Anat. a place in or a division of the body or a part of the body: the abdominal region.
11. Math.
a. Also called domain . an open connected set.
b. the union of such a set and some or all of its boundary points.
[ 1300-50; ME regiun region- (s. of regio ) direction, line, boundary, equiv. to reg ( ere ) to rule + -ion- -ION ]
Syn. 1. area, section, portion. 4. locale, site, tract, quarter.