An Etymological Dictionary of Astronomy and Astrophysics

A → real number which cannot be exactly expressed as a ratio ^a/_b of two integers. Irrational numbers have decimal expansions that neither terminate nor become periodic. Every → transcendental number is irrational. The most famous irrational number is √ 2.

See also: From ir- a prefix meaning “not,” a variant of → in-,

• → rational; → number.