imaginary number
Mathematical term for a number whose square is a negative real number. Often introduced alongside complex numbers.
虚数単位 i は、二乗すると -1 になる数です。
The imaginary unit i is a number that becomes -1 when squared.
高校数学で虚数を初めて学ぶ。
Students first learn about imaginary numbers in high school math.
虚数 (imaginary number) is the mathematical opposite of 実数 (real number) on the complex plane.
imaginary unit
From 虚 (kyo, 'empty' or 'imaginary') + 数 (sū, 'number'), a direct translation of the Western mathematical term 'imaginary number'.