imaginary number
Mathematical term for a number whose square is a negative real number. Often introduced alongside complex numbers.
The imaginary unit i is a number that becomes -1 when squared.
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'.