un·cer·tain | \ ˌən-ˈsər-tᵊn \

Definition of uncertain 

1a : not known beyond doubt : dubious an uncertain claim

b : not having certain knowledge : doubtful remains uncertain about her plans

c : not clearly identified or defined a fire of uncertain origin

2 : not constant : variable, fitful an uncertain breeze

3 : indefinite, indeterminate the time of departure is uncertain

4 : not certain to occur : problematical his success was uncertain

5 : not reliable : untrustworthy an uncertain ally

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Other words from uncertain

uncertainly adverb
uncertainness \ˌən-ˈsər-tᵊn-(n)əs \ noun

Examples of uncertain in a Sentence

The time of departure is still uncertain. We are still uncertain of the truth. She remains uncertain about her plans. I'm uncertain about how to respond. The cause of the fire is uncertain. He has an uncertain temper. They face a financially uncertain future.
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Recent Examples on the Web

Britain seems to be developing a hot-money problem just as its economic future is becoming more uncertain. Paul J. Davies, WSJ, "Why Hot Money Is a Problem for Britain at Just the Wrong Time," 28 June 2018 Beyond early next week, forecasts become more uncertain but there are indications that temperatures may return to somewhat above-normal levels for the month’s second half. Jason Samenow, Washington Post, "A hint of spring arrives as summer steps aside over next 10 days," 4 June 2018 And with the Foxes having lost four of their last five fixtures, the Frenchman's future at the King Power Stadium has become very uncertain. SI.com, "Leicester Eyeing Huddersfield Boss David Wagner With Claude Puel Under Increasing Pressure," 7 May 2018 Senior White House officials say that Mr. Pruitt’s fate has become uncertain. New York Times, "Growing Crisis Threatens Scott Pruitt, E.P.A. Chief, as Top Aides Eye the Exits," 5 Apr. 2018 But Kavanaugh also telegraphed it in no uncertain terms. Aaron Blake, Washington Post, "Brett Kavanaugh’s remarkably political intro speech," 10 July 2018 Just how long that silver lining lasts, given the current climate between Washington and Beijing, is uncertain. Sean Gallagher, Ars Technica, "China producing x86 chips nearly identical to AMD server processors," 9 July 2018 The fate of the Supreme Court’s president, Malgorzata Gersdorf, who turned 65 last November, is uncertain. The Economist, "Poland’s government sacks a third of its Supreme Court," 5 July 2018 Now, Holloway won’t be able to fight at UFC 226, either, and his future is uncertain. Mike Bohn, USA TODAY, "Max Holloway abruptly withdraws from UFC 226 title fight with 'concussion-like symptoms'," 4 July 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'uncertain.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of uncertain

14th century, in the meaning defined at sense 3

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Phrases Related to uncertain

in no uncertain terms

Statistics for uncertain

Last Updated

1 Sep 2018

Look-up Popularity

Time Traveler for uncertain

The first known use of uncertain was in the 14th century

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More Definitions for uncertain



English Language Learners Definition of uncertain

: not exactly known or decided : not definite or fixed

: not sure : having some doubt about something

: not definitely known


un·cer·tain | \ ˌən-ˈsər-tᵊn \

Kids Definition of uncertain

1 : not exactly known or decided on an uncertain amount

2 : not sure They were uncertain of the rules.

3 : not known for sure an uncertain claim

4 : likely to change : not dependable uncertain weather

Other words from uncertain

uncertainly adverb

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Comments on uncertain

What made you want to look up uncertain? Please tell us where you read or heard it (including the quote, if possible).


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