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

  1. excessive, immoderate, or exorbitant; unconscionable: an unreasonable price; unreasonable demands.

  2. 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

Other words for unreasonable

Other words from unreasonable

  • un·rea·son·a·ble·ness, noun
  • un·rea·son·a·bly, adverb

Words Nearby unreasonable

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use unreasonable in a sentence

British Dictionary definitions for unreasonable


/ (ʌnˈriːznəbəl) /

  1. immoderate; excessive: unreasonable demands

  2. refusing to listen to reason

  1. lacking reason or judgment

Derived forms of unreasonable

  • unreasonableness, noun
  • unreasonably, 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