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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Synonym Usage
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
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.
Akio Yoshida, Aeon’s president, said it was highly likely that the explosion was caused by a gas leak of some kind, although the details remain uncertain.
From The Wall Street Journal ● Jul. 29, 2026
The costs this year would probably run into the hundreds of millions, the source said, adding that the exact figure was uncertain and depended on uptake.
From Barron's ● Jul. 29, 2026
"His sudden passing has left his family heartbroken and facing an uncertain future."
From BBC ● Jul. 28, 2026
Warsh has been tight-lipped about the central bank’s path, leaving many Fed-watchers unusually uncertain about what the Fed will do next.
From MarketWatch ● Jul. 26, 2026
Duane froze, uncertain whether the man was addressing him because he was still staring out at the water.
From "The Very, Very Far North" by Dan Bar-el
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.
