imaginary number

American  

noun

Mathematics.

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

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imaginary number British  

noun

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

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imaginary number Scientific  

/ 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

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Etymology

Origin of imaginary number

First recorded in 1905–10

Example Sentences

Later, complex numbers, which are the sum of a real and an imaginary number, gained wide acceptance by mathematicians because of their usefulness for solving complicated mathematical problems.

From Scientific American • Apr. 24, 2023

Like most colleges, Ursinus’ $72,000 list price is an imaginary number; on average, it charges students only about one-third of that.

From Slate • Jul. 25, 2022

Imaginary numbers are distinguished from real numbers because a squared imaginary number produces a negative real number.

From Textbooks • Dec. 1, 2021

If a = 0, then a + bi becomes 0 + bi = bi, and is called a pure imaginary number.

From Textbooks • May 6, 2020

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 Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 7 "Equation" to "Ethics" by Various