imaginary number

noun

, Mathematics.

1. Also called imaginary, pure imaginary number. a complex number having its real part equal to zero.

imaginary number

noun

1. any complex number of the form i b , where i = √–1

imaginary number

/ ĭ-măj′ə-nĕr′ē /

1. A type of complex number in which the multiple of i (the square root of −1) is not equal to zero. Examples of imaginary numbers include 4 i and 2 − 3 i , but not 3 + 0 i (which is just 3).
2. See more at complex number

Word History and Origins

Origin of imaginary number¹

First recorded in 1905–10

Example Sentences

That infinities, infinitesimals, imaginary numbers or other unusual number spaces can be difficult to describe may not seem too surprising.

From Scientific American

Our finding means that imaginary numbers are an essential ingredient in the standard formulation of quantum theory: without them, the theory would lose predictive power.

From Scientific American

It's hard to wrap your head around imaginary numbers.

From Scientific American

“What do you know about imaginary numbers, plane geometry, and vector algebra, Jake?”

From Literature

Descartes thought that these numbers were even worse than negative numbers; he came up with a scornful name for the square roots of negatives: imaginary numbers.

From Literature