noun
class field theory
A branch of algebraic number theory that studies abelian extensions of number fields and local fields.
類体論は代数的整数論の重要な一分野である。
Class field theory is an important branch of algebraic number theory.
From 類体 (class field) + 論 (theory). The term 類体 was coined by Japanese mathematician Teiji Takagi in the early 20th century.