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[im-prob-uh-buh l] /ɪmˈprɒb ə bəl/
not probable; unlikely to be true or to happen:
Rain is improbable tonight.
Origin of improbable
From the Latin word improbābilis, dating back to 1590-1600. See im-2, probable
Related forms
improbably, adverb
improbableness, noun
superimprobable, adjective
superimprobableness, noun
superimprobably, adverb
Can be confused
questionable, doubtful, implausible. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for improbable
Contemporary Examples
Historical Examples
  • A thousand schemes were afloat in his mind about the future, of the most improbable kind.

    Life in London Edwin Hodder
  • But cold reason said that escape was improbable enough for me alone.

    City of Endless Night Milo Hastings
  • It is not improbable that a competitive examination, at this day, might have excluded him from the army.

    Self-Help Samuel Smiles
  • This hypothesis was so improbable that Darwin himself was forced to recognize it.

    The Sexual Question August Forel
  • That nude woman in the very midst of Paris—it's improbable.'

    His Masterpiece Emile Zola
British Dictionary definitions for improbable


not likely or probable; doubtful; unlikely
Derived Forms
improbability, improbableness, noun
improbably, adverb
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
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Word Origin and History for improbable

1590s, from assimilated form of in- (1) "not, opposite of" + probable, or else from Latin improbabilis. Related: Improbably.

Online Etymology Dictionary, © 2010 Douglas Harper
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