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

• 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

Culture provides a grip in an uncertain world, whether racing through growth or crisis mode. —Umang Modi, Forbes.com, 7 July 2025

The future is uncertain for both the league and its players. —Julia Poe, Chicago Tribune, 7 July 2025

This enormous — and uncertain — data center growth should not be Maryland’s responsibility. —David S. Lapp, Baltimore Sun, 7 July 2025

According to a survey conducted for the American Institute of Certified Public Accountants, more than 70% of Americans have felt either cautious or uncertain about their financial situation over the past 12 months. —Corina Vanek, AZCentral.com, 7 July 2025

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