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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:

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

“A story requires a lot of improbable decisions. Maybe they’re not great decisions, but the person doesn’t know that at the time.”

From Los Angeles Times Jul. 22, 2026

Mr. Kraus consulted cetologists to make the improbable premise plausible, but the visceral poetry is all his, and the father-son story hits home.

From The Wall Street Journal Jul. 10, 2026

It was all so quick, so improbable, that if she hadn’t seen it before, if she hadn’t done it herself, she never would have believed it.

From "The Reader" by Traci Chee

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