noun
real number field
In algebra, the field of real numbers under addition and multiplication.
実数体は有理数体の拡大体である。
The real number field is an extension field of the rational number field.
体 is a general term for a field in abstract algebra; 実数体 specifies the field of real numbers.
Compound of 実数 (real number) + 体 (field, in the algebraic sense).