• synonyms


[uhn-thing-kuh-buh l]
See more synonyms for unthinkable on Thesaurus.com
  1. inconceivable; unimaginable: the unthinkable size of the universe.
  2. not to be considered; out of the question: Such a suggestion is unthinkable.
Show More
  1. something that cannot be conceived or imagined, as something too unusual, vague, or disagreeable: Today's unthinkables are tomorrow's realities.
Show More

Origin of unthinkable

late Middle English word dating back to 1400–50; see origin at un-1, thinkable
Related formsun·think·a·bil·i·ty, un·think·a·ble·ness, nounun·think·a·bly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for unthinkable

unbelievable, rare, illogical, extraordinary, unreasonable, unimaginable, uncommon, preposterous, improbable, absurd, implausible, impossible, inconceivable, unlikely, exceptional, outlandish, singular, unique, insupportable, unordinary

Examples from the Web for unthinkable

Contemporary Examples of unthinkable

Historical Examples of unthinkable

British Dictionary definitions for unthinkable


  1. not to be contemplated; out of the question
  2. unimaginable; inconceivable
  3. unreasonable; improbable
Show More
Derived Formsunthinkability or unthinkableness, noununthinkably, 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 unthinkable


early 15c., "too large to be conceived, unimaginable," from un- (1) "not" + thinkable (see think). Meaning "incapable of being framed by thought" is recorded from mid-15c.

Show More
Online Etymology Dictionary, © 2010 Douglas Harper