unthinkable

adjective

un·​think·​able ˌən-ˈthiŋ-kə-bəl 

1

: not capable of being grasped by the mind

2

: being contrary to what is reasonable, desirable, or probable : being out of the question

unthinkability

ˌən-ˌthiŋ-kə-ˈbi-lə-tē 

noun

unthinkably

ˌən-ˈthiŋ-kə-blē 

adverb

Synonyms

• fantastic
• fantastical
• implausible
• inconceivable
• incredible
• incredulous
• unbelievable
• uncompelling
• unconceivable
• unconvincing
• unimaginable

Examples of unthinkable in a Sentence

to most people it seemed unthinkable that such a gentle man could be guilty of such awful crimes

Recent Examples on the Web

And then so many things happened in such a short period of time that were unthinkable: the (introduction of) income tax, labor and environmental regulations, the shorter work week, the breakup of big monopolies and corporate power. —John Blake, CNN Money, 14 June 2025

This was something that was unthinkable just two years ago when Peterson had such a bad season that he was demoted to Triple-A. —Abbey Mastracco, New York Daily News, 12 June 2025

Republicans recently surpassed Democrats in Miami-Dade and are approaching parity in Palm Beach County, which would have been unthinkable a few years ago. —Steve Bousquet, Sun Sentinel, 7 June 2025

The four-episode real-time crime drama, released by Netflix in March, follows the unsettling and hugely gripping fallout from a seemingly unthinkable crime. —Kate Erbland, IndieWire, 29 May 2025

Word History

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing unthinkable

• the unthinkable

Rhymes for unthinkable

• thinkable

Kids Definition

unthinkable

adjective

un·​think·​able ˌən-ˈthiŋ-kə-bəl 

ˈən-

: not to be thought of or considered as possible

unthinkable cruelty