unthinkable
Americanadjective
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inconceivable; unimaginable.
the unthinkable size of the universe.
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not to be considered; out of the question.
Such a suggestion is unthinkable.
noun
-
unthinkables
plural
adjective
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not to be contemplated; out of the question
-
unimaginable; inconceivable
-
unreasonable; improbable
Other Word Forms
Derived Forms
Inflected Forms
Nouns
Etymology
Origin of unthinkable
late Middle English word dating back to 1400–50; see origin at un- 1, thinkable
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
It was the most remarkable and previously unthinkable mathematical achievement in a year full of them.
From The Wall Street Journal ● Sep. 12, 2026
From this perspective, 9/11 is remembered not only as a national trauma but also as a warning about how fear and grief can make policies that once seemed unthinkable appear necessary.
From Salon ● Sep. 8, 2026
Sabalenka losing the top spot seemed unthinkable after a storming start to the season, reaching the Australian Open final and winning the Indian Wells and Miami titles back-to-back.
From BBC ● Sep. 3, 2026
To do so, the 51-year-old Dempsey has to figure out how to maintain the airline’s low-cost edge while embracing amenities that would have once been unthinkable for a budget carrier.
From The Wall Street Journal ● Sep. 1, 2026
Just before the voyage, in January 1941, the unthinkable happened.
From "The Woman All Spies Fear" by Amy Butler Greenfield
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
