DuckCorp Dico

Found one definition

1.                 From Japanese-English FreeDict Dictionary ver. 0.1:
                   
   
   
                   
                     
   圏 /(en)tʃˈaɪniːz(ja)lˈe̞tə/, けん /kˈe̞ɴ/
   1. (noun (common) (futsuumeishi))
    (noun, used as a suffix)
   sphere, circle, range
   2.  [mathematics] category (only in the context of "category theory")