# Definitions for **imaginary number**

### This page provides all possible meanings and translations of the word **imaginary number**

### Random House Webster's College Dictionary

imag′inary num′ber(n.)

a complex number having its real part equal to zero.

**Category:**Math

#### Origin of **imaginary number**:

1905–10

### Princeton's WordNet

complex number, complex quantity, imaginary number, imaginary(noun)

(mathematics) a number of the form a+bi where a and b are real numbers and i is the square root of -1

### Wiktionary

imaginary number(Noun)

A number of the form ai, where a is a real number and i the imaginary unit

### Freebase

Imaginary number

An imaginary number is a number that can be written as a real number multiplied by the imaginary unit, which is defined by its property . An imaginary number has a negative or zero square. For example, is an imaginary number, and its square is . An imaginary number can be added to a real number to form a complex number of the form, where and are called, respectively, the real part and the imaginary part of the complex number. Imaginary numbers can therefore be thought of as complex numbers whose real part is zero. The name "imaginary number" was coined in the 17th century as a derogatory term, as such numbers were regarded by some as fictitious or useless, but today they have a variety of essential, concrete applications in science and engineering.

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"imaginary number." *Definitions.net.* STANDS4 LLC, 2014. Web. 18 Sep. 2014. <http://www.definitions.net/definition/imaginary number>.