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

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.

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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.

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

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

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Like imaginary numbers, we can’t see them or feel them or smell them, even though they are necessary for doing calculations.

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