Is it ensure, insure, or assure?
c.1300, "tract of land of a considerable but indefinite extent," from Anglo-French regioun, Old French region "land, region, province" (12c.), from Latin regionem (nominative regio) "a district, portion of a country, territory, district; a direction, line; boundary line, limit," noun of state from past participle stem of regere "to direct, rule" (see regal). Phrase in the region of "about" (of numbers, etc.) is recorded from 1961.
region re·gion (rē'jən)
An area of the body having natural or arbitrary boundaries.
A portion of the body having a special nervous or vascular supply.
A part of an organ with a special function.
in the social sciences, a cohesive area that is homogeneous in selected defining criteria and is distinguished from neighbouring areas or regions by those criteria. It is an intellectual construct created by the selection of features relevant to a particular problem and the disregard of other features considered to be irrelevant. A region is distinguished from an area, which is usually a broader concept designating a portion of the surface of the Earth. Area boundaries are arbitrary, established for convenience. Regional boundaries are determined by the homogeneity and cohesiveness of the section