irrational
Americanadjective
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without the faculty of reason; deprived of reason.
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without or deprived of normal mental clarity or sound judgment.
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not in accordance with reason; utterly illogical.
irrational arguments.
- Synonyms:
- insensate, ridiculous, unreasonable
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not endowed with the faculty of reason.
irrational animals.
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Mathematics.
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(of a number) not capable of being expressed exactly as a ratio of two integers.
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(of a function) not capable of being expressed exactly as a ratio of two polynomials.
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Algebra. (of an equation) having an unknown under a radical sign or, alternately, with a fractional exponent.
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Greek and Latin Prosody.
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of or relating to a substitution in the normal metrical pattern, especially a long syllable for a short one.
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noting a foot or meter containing such a substitution.
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noun
adjective
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inconsistent with reason or logic; illogical; absurd
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incapable of reasoning
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maths
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not rational
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( as noun )
an irrational
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prosody
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of or relating to a metrical irregularity, usually the occurrence of a long syllable instead of a short one
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denoting a metrical foot where such an irregularity occurs
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Other Word Forms
- irrationally adverb
- irrationalness noun
- nonirrational adjective
- nonirrationalness noun
Etymology
Origin of irrational
First recorded in 1425–75; late Middle English, from Latin irratiōnālis; ir- 2 ( def. ), rational ( def. )
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Fear has a way of making people do irrational things.
Arcilla went on to say that China's Cosco Shipping Lines, the ship's operator, had been victimised by what he called an "irrational fear of radiation" as well as Manila's failure to find a solution.
From Barron's
But there can be risks of AI irrational exuberance overseas, too, making sectors worldwide move in tandem.
From Barron's
In contrast, stock and gold market timers are quite optimistic — even to the point of irrational exuberance.
From MarketWatch
Recognizing this, Masson wrote in 1941, in “Painting is a Wager”: “Towards 1930, five years after the foundation of surrealism, a formidable disaster appeared in its midst: the demagogy of the irrational.”
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
