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.
A couple of weeks after the column External link ran, Greenspan made his famous “irrational exuberance External link” speech, warning investors against getting too excited about tech stocks.
From Barron's
While the motives that drive a knight are often human, political, or both, the logic is as miraculous and irrational as a muddy hedge knight crawling out from under a fallen dragon.
From Salon
Michael Taylor, chair of the Friends of Brockwell Park, told the meeting: "It is irrational to conclude that there is only limited temporary harm in the delicate heritage balance."
From BBC
This was an irrational fear, but this was where Shiffrin was at this point.
Freight was another sector that some analysts said was subjected to irrational AI fears last week.
From MarketWatch
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.
