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 of uncertain

• volatile
• unpredictable
• changeful
• unstable
• inconsistent

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

Ongoing litigation and pending Supreme Court decisions may yet alter the redistricting landscape significantly before November, meaning the final impact of these efforts remains uncertain and could ultimately favor one party over the other depending on judicial rulings. —Los Angeles Times, 1 Mar. 2026

Ben Emons of FedWatch Advisors argued that leadership strikes in Tehran raise regime-change tail risks and leave an uncertain endgame. —Anniek Bao, CNBC, 1 Mar. 2026

Gaither waited for hours in long lines as the situation grew more uncertain. —Timia Cobb breaking News Reporter, Dallas Morning News, 1 Mar. 2026

Advertisement Even if both chambers approve the resolutions, their practical impact remains uncertain. —Nik Popli, Time, 28 Feb. 2026

Word History

First Known Use

14th century, in the meaning defined at sense 3

Phrases Containing uncertain

• in no uncertain terms

Rhymes for uncertain

• bertin
• certain
• curtain

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