[uhn-ree-zuh n]
See more synonyms for unreason on Thesaurus.com
  1. inability or unwillingness to think or act rationally, reasonably, or sensibly; irrationality.
  2. lack of reason or sanity; madness; confusion; disorder; chaos: a world torn by unreason.
verb (used with object)
  1. to upset or disrupt the reason or sanity of: The devious plot soon unreasoned the general.

Origin of unreason

First recorded in 1250–1300, unreason is from the Middle English word un-reson. See un-1, reason
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for unreason

Contemporary Examples of unreason

Historical Examples of unreason

  • Indeed it would be the height of unreason to expect him to be sitting there without that head.

    Little Dorrit

    Charles Dickens

  • And, doctor, I want to apologize for my anger and unreason this morning.

    The Girls at Mount Morris

    Amanda Minnie Douglas

  • You will live bitterly to regret the haste and the unreason of it.'

    Robert Elsmere

    Mrs. Humphry Ward

  • The unreserve and unreason of her passion at last disgusted him.

    A Spoil of Office

    Hamlin Garland

  • My own matriculation at Eugene's College of Unreason was in this wise.

British Dictionary definitions for unreason


  1. irrationality or madness
  2. something that lacks or is contrary to reason
  3. lack of order; chaos
  1. (tr) to deprive of reason
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