unreasonable

adjective

un·​rea·​son·​able
ˌən-ˈrēz-nə-bəl,
-ˈrē-zᵊn-ə-bəl How to pronounce unreasonable (audio)
1
a
: 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
unreasonableness
ˌən-ˈrēz-nə-bəl-nəs
-ˈrē-zᵊn-ə-bəl- How to pronounce unreasonable (audio)
noun
unreasonably
ˌən-ˈrēz-nə-blē
-ˈrē-zᵊn-ə-blē How to pronounce unreasonable (audio)
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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This is a crude and unreasonable attempt to make the discussion into an all-or-nothing affair. Lance Eliot, Forbes.com, 7 Sep. 2025 The Fourth Amendment protects citizens against unreasonable searches and arrests, and requires warrants with probable cause of a crime before seizing a person or property. Landon Mion, FOXNews.com, 6 Sep. 2025 For some of them, especially those animated by the conviction — not entirely unreasonable — that real power in America lies with shadowy, malevolent and unaccountable forces, the Epstein mythology is too central to their worldview to let go of. Michelle Goldberg, Mercury News, 6 Sep. 2025 Callahan was given citations for following too closely, failure to exercise due care to avoid a collision with a horse on the highway, and unreasonable speed, according to authorities. Sam Gillette, PEOPLE, 4 Sep. 2025 See All Example Sentences for unreasonable

Word History

First Known Use

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

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

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Cite this Entry

“Unreasonable.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/unreasonable. Accessed 9 Sep. 2025.

Legal Definition

unreasonable

adjective
un·​rea·​son·​able
: 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
unreasonableness noun
unreasonably adverb

More from Merriam-Webster on unreasonable

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