Word

けん
sphere; circle; range; category (only in the context of "category theory")
Word

大気圏

たいきけん
the atmosphere
Word

圏内

けんない
within the sphere
Word

商圏

しょうけん
business region
Word

圏外

けんがい
outside range; outside orbit
Word

成層圏

せいそうけん
stratosphere
Word

北極圏

ほっきょくけん
Arctic Circle; the Arctic
Word

英語圏

えいごけん
English-speaking world
Word

大圏

たいけん
great circle
Word

首都圏

しゅとけん
the capital city (often Tokyo) area (typically within 50 km of city's centre) (center)