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

Some, including him, publicly called for Khamenei to resign — which was unthinkable at the time, Farahanipour said. —Jack Dolan, Los Angeles Times, 7 Mar. 2026

Yet surrender by the militant group is unlikely, if not outright unthinkable. —Oren Liebermann, CNN Money, 6 Mar. 2026

The two will have a lot to process after the events in Berlin, especially Sam, who’s endured his second unthinkable hijacking situation in a single lifetime. —Barry Levitt, Time, 4 Mar. 2026

Except for those of you who will suffer unthinkable losses and/or be fired this month. —Joe Rexrode, New York Times, 4 Mar. 2026

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