improbable

adjective

im·​prob·​a·​ble (ˌ)im-ˈprä-bə-bəl 

-ˈpräb-bəl

: unlikely to be true or to occur

also : unlikely but real or true

improbability

(ˌ)im-ˌprä-bə-ˈbi-lə-tē 

noun

improbably

(ˌ)im-ˈprä-bə-blē 

-ˈpräb-blē

adverb

Synonyms

• unlikely

Examples of improbable in a Sentence

The team made an improbable comeback.

it seems improbable that the two writers never met since they traveled in the same social circles

Recent Examples on the Web

Bitcoin Has Officially Entered The Chat From memes to mortgages, Bitcoin has entered the mainstream in ways that once seemed improbable. —Becca Bratcher, Forbes.com, 24 July 2025

Private equity is known for its sharp elbows and ruthless dealmaking, so the cohort of decades-long friends running Ares seems improbable. —Leo Schwartz, Fortune, 21 July 2025

Nevertheless, the conspiracists and media should tread lightly and keep in mind that some absurd or improbable theories can cause harm to others. —Chicago Tribune, 18 July 2025

Even with the other guys' admonitions not to, under any circumstances, be themselves, Dee and Charlie's improbable success in charming these scions of the Philly upper crust had the guys — and us — both baffled and anxiously awaiting an ugly twist. —Dennis Perkins, EW.com, 10 July 2025

Word History

Etymology

Middle French or Latin; Middle French, from Latin improbabilis, from in- + probabilis probable

First Known Use

1598, in the meaning defined above

Rhymes for improbable

• probable

Kids Definition

improbable

adjective

im·​prob·​a·​ble (ˈ)im-ˈpräb(-ə)-bəl 

: not probable : unlikely to be true or to occur

improbability

(ˌ)im-ˌpräb-ə-ˈbil-ət-ē 

noun

improbably

(ˈ)im-ˈpräb(-ə)-blē 

adverb