different between fatuous vs irrational

English

Etymology

From Latin fatuus (“foolish, silly, simple”).

Pronunciation

• (Received Pronunciation) IPA^(key): /?fæt.ju.?s/
• (General American) IPA^(key): /?fæt?.u.?s/

Adjective

fatuous (comparative more fatuous, superlative most fatuous)

1. Obnoxiously stupid, vacantly silly, content in one's foolishness.
   • 2004, Frank Tallis, Love Sick: Love as a Mental Illness (page 46)

     A fatuous love affair can easily result in a fatuous marriage. A couple who hardly know each other and, indeed, may not even really like each other, make a commitment that has little chance of being honoured.

Synonyms

• (obnoxiously stupid): childish, imbecilic, inane, insipid, puerile

Related terms

• fatuity
• fatuously
• fatuousness
• infatuate

Translations

English

Etymology

From Latin irrati?n?lis, from ir- + rati?n?lis.

Pronunciation

• enPR: ?r?'sh(?)n?l, IPA^(key): /???æ?.(?.)n?l/

Adjective

irrational (comparative more irrational, superlative most irrational)

1. Not rational; unfounded or nonsensical.
   • 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

   Hyponym: 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

Pronunciation

• IPA^(key): /???at?si?ona?l/, /??at?si?o?na?l/

Adjective

irrational (comparative irrationaler, superlative am irrationalsten)

1. irrational

Declension