irrational number

English Wikipedia has an article on:

irrational number

Wikipedia

irrational number (plural irrational numbers)

1. (mathematics) Any real number that cannot be expressed as a ratio of two integers.

   The square root of a positive integer is an irrational number unless the positive integer is a perfect square, in which case the square root will also be a positive integer.

• rational number

• algebraic number
• transcendental number