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

A theory obeying the rules of quantum physics needs imaginary numbers to describe the real world, two new experiments suggest.

From Science News

Now from a quadric equation we derive, in like manner, the notion of a complex or imaginary number such as is spoken of above.

From Project Gutenberg