# irrational number

### noun Mathematics.

a number that cannot be exactly expressed as a ratio of two integers.

## Nearby words

irradiant, irradiate, irradiation, irradicable, irrational, irrational number, irrationalism, irrationality, irrationalize, irrawaddy, irreal

## Origin of irrational number

First recorded in 1545–55

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Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

## British Dictionary definitions for irrational number

## irrational number

### noun

any real number that cannot be expressed as the ratio of two integers, such as π

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
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## Science definitions for irrational number

## irrational number

[ ĭ-răsh′ə-nəl ]

A number that cannot be expressed as a ratio between two integers and is not an imaginary number. If written in decimal notation, an irrational number would have an infinite number of digits to the right of the decimal point, without repetition. Pi and the square root of 2 (√2) are irrational numbers.

The American Heritage® Science Dictionary
Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

## Culture definitions for irrational number

## Note

The square roots of most whole numbers are irrational numbers.

The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.