adjective un·rea·son·able \ ˌən-ˈrēz-nə-bəl , -ˈrē-zᵊn-ə-bəl \
|Updated on: 14 Aug 2018

Definition of unreasonable

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


play \ˌən-ˈrēz-nə-bəl-nəs, -ˈrē-zᵊn-ə-bəl-\ noun


play \ˌən-ˈrēz-nə-blē, -ˈrē-zᵊn-ə-blē\ adverb

Examples of unreasonable in a Sentence

  1. I told him that I wouldn't pay unless he sent me a replacement. Am I being unreasonable?

  2. You are entitled to compensation for unreasonable delays.

Recent Examples of unreasonable from the Web

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.

First Known Use of unreasonable

14th century

in the meaning defined at sense 1a

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UNREASONABLE Defined for English Language Learners


Definition of unreasonable for English Language Learners

  • : not fair, sensible, or appropriate : not reasonable

UNREASONABLE Defined for Kids


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

Definition of unreasonable for Students

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


\-blē\ adverb

Law Dictionary


adjective un·rea·son·able

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 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 violated
  • U.S. Constitution amend. IV
— see also search, seizure





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