1 [geography] In geography, an area usually distinguished by common cultural or physical characteristics, such as Southern California, Western Europe, or Southeast Asia.
2 [data models] A set of contiguous cells with the same value.
3 [ESRI software] In the coverage data structure, a polygon feature made up of multiple polygons that may be separate, overlapping, nested, or adjacent. The polygons that compose a region are stored in a polygon feature class, while the region is stored in a subclass of this feature class. A region has its own attributes but no shape geometry; its shape is defined by the shape geometry of the polygons that compose it.