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

But other officials told me that Trump indeed has toyed with the idea, which would have been unthinkable under previous Democratic and Republican presidents. —Shane Harris, The Atlantic, 6 Mar. 2025

America's fraying relationship with longtime allies is driving global economic shifts that were unthinkable just months ago. —Courtenay Brown, Axios, 6 Mar. 2025

The biggest spotlight has been on Mr. Trump’s very public effort to broker a quick peace in Ukraine, which has entailed previously unthinkable U.S. deference to Moscow’s wishes. —Fred Weir, The Christian Science Monitor, 5 Mar. 2025

But there are hints, here, of a substance that might have been unusual on TV at the time and is certainly unthinkable today. —Bill Wyman, Vulture, 28 Feb. 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