uncertain
Americanadjective
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not definitely ascertainable or fixed, as in time of occurrence, number, dimensions, or quality.
- Synonyms:
- unpredictable, unsure
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not confident, assured, or free from hesitancy.
an uncertain smile.
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not clearly or precisely determined; indefinite; unknown.
a manuscript of uncertain origin.
- Synonyms:
- undetermined, unsettled
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vague; indistinct; not perfectly apprehended.
an abstruse novel with uncertain themes.
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subject to change; variable; capricious; unstable.
a person of uncertain opinions.
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ambiguous; unreliable; undependable.
Her loyalties are uncertain.
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dependent on chance or unpredictable factors; doubtful; of unforeseeable outcome or effect.
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unsteady or flickering, as light; of changing intensity or quality.
- Synonyms:
- irregular
adjective
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not able to be accurately known or predicted
the issue is uncertain
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not sure or confident (about)
a man of uncertain opinion
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not precisely determined, established, or decided
uncertain plans
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not to be depended upon; unreliable
an uncertain vote
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liable to variation; changeable
the weather is uncertain
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unambiguously
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forcefully
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Related Words
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.
Other Word Forms
- uncertainly adverb
- uncertainness noun
Etymology
Origin of uncertain
First recorded in 1250–1300; Middle English; un- 1 + certain
Explanation
To be uncertain is to be unsure of something. Also, uncertain things are undecided, unknown, or doubtful in some way. If you're certain of something, you're sure of it. When you're uncertain, you don't know. If you don't know the answer to a math question, you're uncertain. If you can't remember where you parked your car, you're uncertain about its location. Also, anything unknown or up in the air in uncertain. Trying to be a famous actor is an uncertain path. Gambling money on horses is very uncertain. And, it's certainly hard to plan for an uncertain future.
Vocabulary lists containing uncertain
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.
While scientists have long known the region was eventually forested, the timing of when trees first took hold and how suitable the environment was for early humans has remained uncertain.
From Science Daily • Apr. 17, 2026
Seres, based in the south-west city of Chongqing, has not announced any cars that have toilets and it is uncertain if any will be made.
From BBC • Apr. 17, 2026
Economists predict the current wave of inflation is likely to peter out later in the year, but they are uncertain as to when and by how much.
From MarketWatch • Apr. 15, 2026
Bank executives describe the U.S. economy and American consumers as resilient despite an uncertain environment and the rising costs of household items such as utility bills and gasoline.
From Barron's • Apr. 15, 2026
Neither would they limit themselves to the slow and equally uncertain process of seeking justice within the courts.
From "The Best of Enemies" by Osha Gray Davidson
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
