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

Our data is optimistic, but the politics is uncertain. —James Morton Turner, Discover Magazine, 9 Nov. 2024

Even with a Republican Congress, some of this could prove difficult — and the potential fallout is uncertain at best. —Carl Leubsdorf, The Mercury News, 7 Nov. 2024

So, what can parents do to model equanimity and grace in these very uncertain and high-pressure times? —Chloe Schama, Vogue, 5 Nov. 2024

The fate of The Real Housewives of New Jersey’s season 15 is uncertain, star Dolores Catania said. —Charna Flam, People.com, 5 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