improbable

adjective

im·​prob·​a·​ble (ˌ)im-ˈprä-bə-bəl 

-ˈpräb-bəl

: unlikely to be true or to occur

an improbable story

also : unlikely but real or true

their improbable come-from-behind victory

improbability

(ˌ)im-ˌprä-bə-ˈbi-lə-tē 

noun

improbably

(ˌ)im-ˈprä-bə-blē 

-ˈpräb-blē

adverb

Synonyms of improbable

• 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

Among the most delightful episodes of English-language biography is Boswell’s account of an improbable dinner party in the fateful year of 1776 that was attended by the hyper-radical Wilkes and the reactionary Samuel Johnson, who became and stayed friends. —Adam Gopnik, New Yorker, 8 June 2026

The upbeat outlook suggests Chief Executive Officer Lip-Bu Tan is making progress on a once-improbable turnaround. —Bloomberg, Mercury News, 8 June 2026

Our identities added a deep layer of complexity to an already improbable undertaking. —Diana Rodriguez, Time, 8 June 2026

Meanwhile, Russian teenager Mirra Andreeva won the women’s singles final Saturday to claim her first Grand Slam title, ending qualifier Maja Chwalińska’s improbable run with a 6-3, 6-2 victory. —Kayla Hayempour, NBC news, 7 June 2026

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