irrational

From Latin irratiōnālis, from ir- + ratiōnālis.

• enPR: ĭră'sh(ə)nəl, IPA^(key): /ɪˈɹæʃ.(ə.)nəl/

• Audio (Southern England)

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• Rhymes: -æʃənəl

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.

   Antonym: rational

   Hyponyms: transcendental, uncomputable

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.

• “irrational”, in OneLook Dictionary Search.
• “irrational”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.
• “irrational”, in The American Heritage Dictionary of the English Language, 5th edition, Boston, Mass.: Houghton Mifflin Harcourt, 2016, →ISBN.
• “irrational”, in Collins English Dictionary.
• “irrational” (US) / “irrational” (UK) in Macmillan English Dictionary.

• irrationell

• IPA^(key): /ˈɪʁat͡si̯onaːl/, /ɪʁat͡si̯oˈnaːl/

• Audio

  (file)

irrational (strong nominative masculine singular irrationaler, comparative irrationaler, superlative am irrationalsten)

1. irrational