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

Not long ago, trying to flip a seat from red to blue by promising to raise taxes on the rich was considered unthinkable. — Sen. Elizabeth Warren, Time, 5 Nov. 2026

Raman’s position on the precipice of ascending to the mayoralty would have seemed nearly unthinkable at the start of the year, when Bass’ challengers included Pratt, former LAUSD Supt. — Clara Harter, Los Angeles Times, 4 Nov. 2026

The Dallas Cowboys have somehow lost in yet another unthinkable manner, blowing a two-score lead with just over two minutes left to fall to the lowly Arizona Cardinals 33-30 in overtime Sunday at AT&T Stadium. — Nick Harris, Fort Worth Star-Telegram, 1 Nov. 2026

From 1968 to 1974, its Apollo program landed on the Moon six separate times, a pace that seems unthinkable today. — Frank Landymore, Futurism, 29 Oct. 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