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Synonyms

improbable

American  
[im-prob-uh-buhl] / ɪmˈprɒb ə bəl /

adjective

  1. not probable; unlikely to be true or to happen.

    Rain is improbable tonight.

    Synonyms:
    implausible, doubtful, questionable

improbable British  
/ ɪmˈprɒbəbəl /

adjective

  1. not likely or probable; doubtful; unlikely

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of improbable

From the Latin word improbābilis, dating back to 1590–1600. See im- 2, probable

Explanation

Your parents might tell you it's improbable that they'll buy you a car when you turn 16. Since improbable means something is unlikely but not impossible, your optimism allows you to keep hoping. The adjective improbable also means statistically unlikely to happen. You might be afraid to fly, but the odds of a plane crash are so low that such an event is improbable. Improbable also means something that is so outrageous that you'd never admit you believed in it. You know the existence of the Loch Ness Monster is improbable, but that doesn't stop you from looking for it when you travel to Scotland.

Keep Reading on Vocabulary.com

Vocabulary lists containing improbable

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

See Examples For:

Joshua Kushner’s $12.5 billion deal to acquire the team with Bob Iger, Disney senior adviser and former CEO, marks another chapter in the improbable story of one family’s American journey.

From The Wall Street Journal Aug. 15, 2026

Lovers and ex-guerrillas Derlis Aizama and Daniel Paredes recently laid down arms to start a family, but Colombia's incoming hard-right administration might upend their improbable attempt at civilian life.

From Barron's Aug. 4, 2026

The turkey was fine, and the cheese was technically cheese, though the sandwich had achieved the improbable condition of being simultaneously refrigerator-cold and slightly melted.

From Salon Jul. 30, 2026

It seems improbable that Fifa will back down in the same manner.

From BBC Jul. 29, 2026

You can never tell when new things may be starting up from improbable lines of work.

From "The Lives of a Cell" by Lewis Thomas

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