• synonyms


[uhn-ree-zuh-nuh-buh l, -reez-nuh-]
See more synonyms for unreasonable on Thesaurus.com
  1. not reasonable or rational; acting at variance with or contrary to reason; not guided by reason or sound judgment; irrational: an unreasonable person.
  2. not in accordance with practical realities, as attitude or behavior; inappropriate: His Bohemianism was an unreasonable way of life for one so rich.
  3. excessive, immoderate, or exorbitant; unconscionable: an unreasonable price; unreasonable demands.
  4. not having the faculty of reason.
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Origin of unreasonable

First recorded in 1300–50, unreasonable is from the Middle English word unresonabel. See un-1, reasonable
Related formsun·rea·son·a·ble·ness, nounun·rea·son·a·bly, adverb


See more synonyms for unreasonable on Thesaurus.com
1, 2. senseless, foolish, silly. 2. preposterous, absurd, stupid, nonsensical. 3. extravagant.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for unreasonableness

Historical Examples

  • But the unreasonableness of such a suspicion was patent, and Mr Verloc held his tongue.

    The Secret Agent

    Joseph Conrad

  • What I had done I had done as much to win Roxalanne to me as to win her from her own unreasonableness.

  • It was Tom who pointed out the unreasonableness of emotion in making this demand.

  • Her wishes had none of the unreasonableness of dying fancies.

    Rene Mauperin

    Edmond de Goncourt and Jules de Goncourt

  • Thus he sat wondering, dismayed by the unreasonableness of women.

    The Dark Flower

    John Galsworthy

British Dictionary definitions for unreasonableness


  1. immoderate; excessiveunreasonable demands
  2. refusing to listen to reason
  3. lacking reason or judgment
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Derived Formsunreasonableness, noununreasonably, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for unreasonableness



mid-14c., from un- (1) "not" + reasonable. Related: Unreasonably.

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Online Etymology Dictionary, © 2010 Douglas Harper