英和和英

発音

• enPR: ĭră'sh(ə)nəl, IPA: /ɪˈɹæʃ.(ə.)nəl/
• 韻: -æʃənəl

形容詞

irrational (comparative more irrational, superlative most irrational)

1. Not rational; unfounded, nonsensical or wrong-headed.

   an irrational decision

   • July 18, 2012, Scott Tobias, AV Club The Dark Knight Rises[1]

     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.

   Antonym: rational

   The number π is irrational.

   Hyponyms: transcendental, uncomputable

派生語

Collocations

名詞

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.

Further reading

• “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.