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 of unthinkable

• incredible
• unlikely
• incredulous
• impossible
• inconceivable
• unimaginable
• unbelievable

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

Together, the deals would have been unthinkable just a few years ago, when Cairo was part of the embargo of Qatar and the former Syrian regime was a pariah. —Mohammed Sergie, semafor.com, 7 Jan. 2026

Removing Tonali early would have been unthinkable just a few weeks ago, but he was also taken off against Palace and continues to labour through games, whereas Miley has flourished recently. —Chris Waugh, New York Times, 7 Jan. 2026

Its oil production, the beating heart of the country, dropped to less than 400,000 barrels a day, a figure once unthinkable. —Dallas Morning News, 3 Jan. 2026

Many of Lambert’s recent cases have involved grave crimes, of the sort that society considers unthinkable. —Rosa Lyster, Harpers Magazine, 30 Dec. 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