inside (a region, area, etc.); within the range (of); within the sphere (of influence, etc.)
outside (a region, area, etc.); out of range (of a mobile network, radar, etc.); outside the sphere (of influence, etc.); out of contention; out of reach
safety zone; buffer (e.g. against defeat)
one's daily milieu; neighbourhood; neighborhood; zone of life; sphere of life
Greater Tokyo Metropolitan area; metropolitan area (of a capital)
economic bloc; ecosystem (of services, goods, etc. within a company or consortium)
polar circle; polar region
(within) walking distance
English-speaking world; English-speaking countries; Anglosphere
gravitational sphere (of a celestial body); gravitational field
Arctic Circle; the Arctic
urban area; metropolitan area; metropolitan region
greater metropolitan area; megalopolis; conurbation
business region; marketing area; commercial sphere; trading area; region in which a business operates
communist bloc; Iron Curtain
air defense identification zone; ADIZ
emphasis mark (used in Japanese text in a way similar to underlining)
Islamic world; Muslim world
gravitational field (of a celestial body); sphere of gravitation; gravisphere
Antarctic Circle; the Antarctic
German-speaking countries; German language sphere
French-speaking world; francophone world; francophonie
wider Kinki region (Osaka, Kyoto, Nara, Shiga, Wakayama and Fukui prefectures); wider Kansai area
countries where Chinese characters are used or were historically used
eurozone; euro zone; euro area
Greater China (incl. Hong Kong, Macao, Taiwan and sometimes Singapore); Sinosphere
sphere (e.g. of knowledge, influence)
public sphere; public domain
Spanish-speaking world; Spanish-speaking countries
Tokyo area (esp. in ref. to Tokyo, Kanagawa, Saitama and Chiba); Tokyo region
sinophone world; Chinese-speaking world
Chūkyō metropolitan area (most of Aichi, and parts of Gifu and Mie prefectures; centered around Nagoya); Chūkyō region
surroundings; vicinity; periphery
gnomonic chart; great-circle chart; great-circle map
hour circle; circle of declination
gnomonic projection (in cartography); central projection
traffic area; traffic block
harm zone; people who will suffer the negative effects of new public facilities, infrastructure, etc. (e.g. pollution)
beneficiary zone; people who will enjoy the benefits of new public facilities, infrastructure, etc.
Kansai area; Kansai region
Grothendieck's Galois theory