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

This Western fixation has produced zany — and harmful — results that would be unthinkable in an ethical system that has stood the test of time. —Wilfred Reilly, National Review, 15 Feb. 2025

After bolstering their World Series-winning roster with a hefty winter spending spree, anything short of the playoffs is unthinkable. —Houston Mitchell, Los Angeles Times, 11 Feb. 2025

For most of human history, this would have been unthinkable. —Dylan Scott, Vox, 5 Feb. 2025

The conditions are unthinkable — a mass casualty site on the frigid Potomac. —Cuneyt Dil, Axios, 31 Jan. 2025

Word History

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing unthinkable

• the unthinkable

Kids Definition

unthinkable

adjective

un·​think·​able ˌən-ˈthiŋ-kə-bəl 

ˈən-

: not to be thought of or considered as possible

unthinkable cruelty