圏けん論ろんMeanings1nouncategory theorymathematicsA branch of mathematics dealing with abstract structures and relationships between them.圏けん論ろんは数すう学がくの多おおくの分ぶん野やで使つかわれている。Category theory is used in many areas of mathematics.彼かれは圏けん論ろんの研けん究きゅう者しゃだ。He is a researcher in category theory.