English

Adjective

irrational ‎(comparative more irrational, superlative most irrational)

1. Not rational; unfounded or nonsensical.

   an irrational decision

   • July 18, 2012, Scott Tobias, AV Club The Dark Knight Rises

     Where the Joker preys on our fears of random, irrational acts of terror, Bane has an all-consuming, dictatorial agenda that’s more stable and permanent, a New World Order that’s been planned out with the precision of a military coup.

2. (mathematics, arithmetic, number theory, not comparable) Of a real number, that cannot be written as the ratio of two integers.

   The number π is irrational.

Antonyms

• (mathematics): rational

Hyponyms

• (mathematics): transcendental

Derived terms

Translations

Noun

irrational ‎(plural irrationals)

1. A real number that can not be expressed as the quotient of two integers, an irrational number.
   • 1946, Bertrand Russell, History of Western Philosophy, I.24:

     The square root of 2, which was the first irrational to be discovered, was known to the early Pythagoreans, and ingenious methods of approximating to its value were discovered.

Translations

German

Alternative forms

• irrationell

Adjective

irrational ‎(comparative irrationaler, superlative am irrationalsten)

1. irrational

Declension