[uhn-ree-zuh n]


inability or unwillingness to think or act rationally, reasonably, or sensibly; irrationality.
lack of reason or sanity; madness; confusion; disorder; chaos: a world torn by unreason.

verb (used with object)

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. 2019

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



irrationality or madness
something that lacks or is contrary to reason
lack of order; chaos


(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