un·​rea·​son·​able | \ˌən-ˈrēz-nə-bəl, -ˈrē-zᵊn-ə-bəl\

Definition of unreasonable 

1a : not governed by or acting according to reason unreasonable people

b : not conformable to reason : absurd unreasonable beliefs

2 : exceeding the bounds of reason or moderation working under unreasonable pressure

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Other Words from unreasonable

unreasonableness \ˌən-​ˈrēz-​nə-​bəl-​nəs, -​ˈrē-​zᵊn-​ə-​bəl-​ \ noun
unreasonably \ˌən-​ˈrēz-​nə-​blē, -​ˈrē-​zᵊn-​ə-​blē \ adverb

Examples of unreasonable in a Sentence

I told him that I wouldn't pay unless he sent me a replacement. Am I being unreasonable? You are entitled to compensation for unreasonable delays.

Recent Examples on the Web

But while her frequent moisturizing may seem excessive, Marchbein says that moisturizing more than twice a day isn't unreasonable. Marci Robin, Allure, "Elizabeth Hurley Moisturizes Her Skin 10 Times a Day," 4 Oct. 2018 The legal question for the justices was whether prosecutors violated the Fourth Amendment, which bars unreasonable searches, by collecting without warrant vast amounts of data from cellphone companies that showed Mr. Carpenter’s movements. Adam Liptak, New York Times, "In Ruling on Cellphone Location Data, Supreme Court Makes Statement on Digital Privacy," 22 June 2018 The Civil Rights Act guarantees citizens’ constitutionally protected civil rights, including the Fourth Amendment’s guarantee of freedom from unreasonable searches and seizures. Michael Mccann, SI.com, "Inside Sterling Brown’s compelling lawsuit against the Milwaukee Police Department and City of Milwaukee," 19 June 2018 The Republican bet, not unreasonable, was that a growing economy would take care of that gap. William Mcgurn, WSJ, "Nancy Pelosi, the Sequel," 29 Oct. 2018 Making the group seem unreasonable, and also taking things that were sort of sensationalized in ways that were ... Recode Staff, Recode, "Full transcript: Data for Democracy policy head Renée DiResta answers disinformation questions on Too Embarrassed to Ask," 14 July 2018 Recently, the Supreme Court has appeared more eager to protect Americans' digital property from unreasonable search, not just their physical property. Issie Lapowsky, WIRED, "Kavanaugh on the Supreme Court Could Spell Trouble for Tech," 10 July 2018 One, not unreasonable, objection was the length of trip half way around the world by ship and the costs of doing so. SI.com, "World Cup Countdown: 17 Weeks to Go - Did India Drop Out of 1950 Because They Refused to Wear Boots?," 25 Feb. 2018 He was found in breach of six department policies, including using unreasonable and excessive force in the situation and not turning on his body camera. Jason Pohl, azcentral, "Ex-Flagstaff cop in viral punch video: 'I don't believe I did anything wrong'," 17 May 2018

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

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First Known Use of unreasonable

14th century, in the meaning defined at sense 1a

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Last Updated

4 Dec 2018

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The first known use of unreasonable was in the 14th century

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English Language Learners Definition of unreasonable

: not fair, sensible, or appropriate : not reasonable


un·​rea·​son·​able | \ˌən-ˈrē-zᵊn-ə-bəl \

Kids Definition of unreasonable

: not fair, sensible, appropriate, or moderate an unreasonable schedule unreasonable behavior an unreasonable fear

Other Words from unreasonable

unreasonably \-​blē \ adverb



Legal Definition of unreasonable 

: not reasonable : beyond what can be accepted: as

a : clearly inappropriate, excessive, or harmful in degree or kind an unreasonable delay an unreasonable restraint of trade

b : lacking justification in fact or circumstance an unreasonable inference especially : irrational sense b the agency decision was unreasonable

c : not supported by a warrant or by a valid exception to a warrant requirement (as when there is reasonable suspicion) and therefore unconstitutional the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violatedU.S. Constitution amend. IV — see also search, seizure

Other Words from unreasonable

unreasonableness noun
unreasonably adverb

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the figure or shape of a crescent moon

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