noun
quadratic field
In algebraic number theory, a quadratic field is a field extension of the rational numbers of degree 2. It is obtained by adjoining the square root of a square-free integer.
二次体の整数環について研究している。
I am researching the ring of integers of a quadratic field.
実二次体と虚二次体では性質が異なる。
Real quadratic fields and imaginary quadratic fields have different properties.
円分体 (cyclotomic field) is a field obtained by adjoining a root of unity, which can be of degree higher than 2, unlike 二次体.
Compound of 二次 (niji, 'quadratic, second-order') and 体 (tai, 'field' in the mathematical sense). The term is a direct calque from English 'quadratic field'.