irrational

adjective

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ir·ra·tio·nal | \ i-ˈra-sh(ə-)nəl

, ˌi(r)- \

Definition of irrational

(Entry 1 of 2)

: not rational: such as

a(1) : lacking usual or normal mental clarity or coherence

(2) : not endowed with reason or understanding

b : not governed by or according to reason irrational fears

c Greek and Latin prosody

(1) of a syllable : having a quantity other than that required by the meter

(2) of a foot : containing such a syllable

d(1) : being an irrational number an irrational root of an equation

(2) : having a numerical value that is an irrational number a length that is irrational

irrational

noun

Definition of irrational (Entry 2 of 2)

1 : an irrational being

2 : irrational number

Other Words from irrational Synonyms & Antonyms Example Sentences Learn More About irrational

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Other Words from irrational

Adjective

irrationality \ i-ˌra-shə-ˈna-lə-tē

, ˌi(r)- \ noun

irrationally \ i-ˈra-sh(ə-)nə-lē

, ˌi(r)- \ adverb

Examples of irrational in a Sentence

Adjective He became irrational as the fever got worse. She had an irrational fear of cats.

Recent Examples on the Web: Adjective And whatever their reasoning, however irrational, a handful of players are standing by their convictions. — BostonGlobe.com, 2 Oct. 2021 The goal of combining all these disciplines is to ultimately learn about the mental, emotional, irrational, and behavioral nuances governing our buying habits. — Prince Ghuman, Forbes, 2 Oct. 2021 This duality makes her character -- and the movie -- all the more challenging, as we're asked to grapple with the rational and the irrational, the acceptable and the otherworldly. — CNN, 17 Sep. 2021 In place of Mackay’s intuitive insights into crowd madness, Bernstein draws on research in the field of behavioral psychology to distinguish between rational and irrational economic behavior. — Edward Chancellor, The New York Review of Books, 19 Aug. 2021 Yet historians know that American drug laws are anything but irrational, arbitrary or absurd. — Washington Post, 23 July 2021 The status-quo managers are not being entirely irrational. — Steve Denning, Forbes, 13 Sep. 2021 The era of irrational exuberance was already running on fumes by the time the Twin Towers fell. — Cynthia Littleton, Variety, 27 Aug. 2021 You may be tempted to display irrational or unnecessarily mean behavior due to your own internal conflict. — Meghan Ros, Glamour, 1 Sep. 2021 Recent Examples on the Web: Noun But feeling anxious right now is not at all out of line or irrational. — Jessica Dulong, CNN, 31 Aug. 2021 Attempting to appease the loudest to the detriment of the community only emboldens the irrational and silences those looking to have productive conversation. — Benjamin Ayanian, Star Tribune, 5 May 2021 To believe in the return of a long-dead child reflects the anguish of the believer and, of course, a tendency to embrace the irrational. — Dorothy Rabinowitz, WSJ, 29 Apr. 2021 We are all steered by a mixture of the rational and the irrational. — Christopher Beha, Harpers Magazine, 5 Jan. 2021 In the battle between the infinitely large and the infinitely small, Dirichlet had to find the right balance to prevent some irrationals from slipping through the cracks. — Quanta Magazine, 10 Mar. 2020 These unwieldy numbers have plagued mathematicians since the ancient Greeks; indeed, legend has it that Hippasus was drowned for suggesting irrationals existed. — Leila Sloman, Scientific American, 16 Sep. 2019 Instead, mathematicians ask about the proportion of the total number of irrationals corralled by each fraction. — Quanta Magazine, 14 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'irrational.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.