[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.

Nearby words

  1. unreality,
  2. unrealizable,
  3. unrealized,
  4. unreally,
  5. unreason,
  6. unreasonable behaviour,
  7. unreasoning,
  8. unreckonable,
  9. unrecognizable,
  10. unrecognized

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

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

Examples from the Web for unreasonable

British Dictionary definitions for unreasonable



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 unreasonable



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

Online Etymology Dictionary, © 2010 Douglas Harper