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[uhn-sur-tn] /ʌnˈsɜr tn/
not definitely ascertainable or fixed, as in time of occurrence, number, dimensions, or quality.
not confident, assured, or free from hesitancy:
an uncertain smile.
not clearly or precisely determined; indefinite; unknown:
a manuscript of uncertain origin.
vague; indistinct; not perfectly apprehended:
an abstruse novel with uncertain themes.
subject to change; variable; capricious; unstable:
a person of uncertain opinions.
ambiguous; unreliable; undependable:
Her loyalties are uncertain.
dependent on chance or unpredictable factors; doubtful; of unforeseeable outcome or effect.
unsteady or flickering, as light; of changing intensity or quality.
Origin of uncertain
Middle English word dating back to 1250-1300; See origin at un-1, certain
Related forms
uncertainly, adverb
uncertainness, noun
1. unsure, unpredictable. 3. unsettled, undetermined. 8. irregular.
Synonym Study
1.Uncertain, insecure, precarious imply a lack of predictability. That which is uncertain is doubtful or problematical; it often involves danger through an inability to predict or to place confidence in the unknown: The time of his arrival is uncertain. That which is insecure is not firm, stable, reliable, or safe, and hence is likely to give way, fail, or be overcome: an insecure foundation, footing, protection. Precarious suggests great susceptibility to failure, or exposure to imminent danger: a precarious means of existence. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for uncertain
Contemporary Examples
Historical Examples
  • You may have noticed that night at the Oldakers'—well, women, Mr. Bines, are uncertain.

    The Spenders Harry Leon Wilson
  • There appears to be a great number of horses', but am uncertain if there are any camel-tracks.

  • With his bag in hand, he wandered through the streets, uncertain what to do or where to go.

    Life in London Edwin Hodder
  • Her face was close to his, else he could not have caught the uncertain murmuring.

    Within the Law Marvin Dana
  • Then some one—who it was is uncertain—ordered the bugler to sound the "charge."

    The Story of the Malakand Field Force Sir Winston S. Churchill
British Dictionary definitions for uncertain


not able to be accurately known or predicted: the issue is uncertain
when postpositive, often foll by of. not sure or confident (about): a man of uncertain opinion
not precisely determined, established, or decided: uncertain plans
not to be depended upon; unreliable: an uncertain vote
liable to variation; changeable: the weather is uncertain
in no uncertain terms
  1. unambiguously
  2. forcefully
Derived Forms
uncertainly, adverb
uncertainness, noun
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 uncertain

c.1300, "of indeterminate time or occurrence," from un- (1) "not" + certain (adj.). Meaning "not fully confident" is recorded from late 14c. (implied in uncertainty). Related: Uncertainly.

Online Etymology Dictionary, © 2010 Douglas Harper
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Idioms and Phrases with uncertain


The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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