uncertain

adjective

un·​cer·​tain ˌən-ˈsər-tᵊn 

1

a

: 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

uncertainly adverb

uncertainness

ˌən-ˈsər-tᵊn-(n)əs 

noun

Synonyms

• capricious
• changeable
• changeful
• fickle
• flickery
• fluctuating
• fluid
• inconsistent
• inconstant
• mercurial
• mutable
• skittish
• temperamental
• unpredictable
• unsettled
• unstable
• unsteady
• variable
• volatile

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.

Recent Examples on the Web

Although the potential consequences are uncertain, the tariffs, which are a tax on goods that are imported, will likely hurt countries in Asia that rely on sales to the United States to boost their economies. —Rosa De Acosta, CNN, 27 Nov. 2024

The amount is uncertain because the formula for the seller’s payment generally depends on facts that will not be known until the case is resolved. —Robert W. Wood, Forbes, 27 Nov. 2024

Thomas said as much as 7 inches of snow could fall during the event, but the forecast is still uncertain. —Dan Perry, Newsweek, 26 Nov. 2024

The storm system's track was still somewhat uncertain Tuesday, but forecasters said below-average temperatures in the Northeast — especially in interior areas — could determine whether different locations in the region are hit with rain or snow. —Emily Mae Czachor, CBS News, 26 Nov. 2024

Word History

First Known Use

14th century, in the meaning defined at sense 3

Phrases Containing uncertain

• in no uncertain terms

Kids Definition

uncertain

adjective

un·​cer·​tain ˌən-ˈsərt-ᵊn 

ˈən-

1

: not definite or fixed

an uncertain quantity

2

a

: not sure

uncertain of the truth

b

: not known for sure

an uncertain claim

3

: likely to change : not dependable

uncertain weather

uncertainly adverb