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.
The stock market behaves a lot like a toddler: a short attention span, active imagination and some irrational fears.
Just before Christmas, the court ruled that the government's assessment of damage to national security "should have been accepted by the coroner" unless it was plainly irrational or there was no supporting evidence.
From BBC
In the past week, the home secretary has announced a number of sweeping changes to policing, having described the current structures as "irrational".
From BBC
“It was a humbling experience for a lot of sophisticated financial investors to see such an irrational behavior driving markets so violently,” says Mudrick.
From Barron's
But that logic, in this case, is fundamentally irrational.
From Barron's
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.
