[uhn-ree-zuh-nuh-buhl, -reez-nuh-]


not reasonable or rational; acting at variance with or contrary to reason; not guided by reason or sound judgment; irrational: an unreasonable person.
not in accordance with practical realities, as attitude or behavior; inappropriate: His Bohemianism was an unreasonable way of life for one so rich.
excessive, immoderate, or exorbitant; unconscionable: an unreasonable price; unreasonable demands.
not having the faculty of reason.

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

Synonyms for unreasonable

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for unreasonably


Examples from the Web for unreasonably

Contemporary Examples of unreasonably

Historical Examples of unreasonably

  • This act of justice has been unreasonably delayed in the case of some of them.

  • That local rates are unreasonably high, as compared with through rates.

    The Railroad Question

    William Larrabee

  • On the third day she had felt almost angry with him unreasonably.

    A Spirit in Prison

    Robert Hichens

  • Poor Jed, miserable and most unreasonably conscience-stricken, writhed in his chair.


    Joseph C. Lincoln

  • Instead his opposition was just as violent and, to his son's mind, as unreasonably absurd.


    Joseph C. Lincoln

British Dictionary definitions for unreasonably



immoderate; excessiveunreasonable demands
refusing to listen to reason
lacking reason or judgment
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 unreasonably



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

Online Etymology Dictionary, © 2010 Douglas Harper