irrational number

noun

Mathematics.

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

irrational number

noun

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

irrational number

1. 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.

irrational number

1. A number that cannot be expressed as the ratio of two whole numbers.

The square roots of most whole numbers are irrational numbers.

Word History and Origins

Origin of irrational number¹

First recorded in 1545–55