certainly

adverb

cer·​tain·​ly ˈsər-tᵊn-lē 

1

: in a manner that is certain : with certainty

2

: it is certain that : assuredly

Synonyms of certainly

• definitely
• surely
• sure
• clearly
• probably
• really

Examples of certainly in a Sentence

It will certainly rain tomorrow.

This year's festival was certainly much better than last year's.

I'm certainly going to try.

The new version is most certainly easier to use.

The snake that bit her was almost certainly poisonous.

Recent Examples on the Web

And while the hours and hours of practice certainly honed the sisters’ skills, their parents can’t explain where the girls got their immense physical gifts. —Los Angeles Times, 30 May 2026

Some clerical tasks certainly disappeared or changed. —Christopher Marquis, Time, 30 May 2026

This week, the call came from someone — certainly not a novice — who found himself in an uncomfortable situation. —Allen Buchanan, Oc Register, 30 May 2026

This growing interest in Roth IRAs certainly makes sense. —Andreina Rodriguez, CNBC, 30 May 2026

Word History

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing certainly

• certainly not

Rhymes for certainly

• uncertainly

Kids Definition

certainly

adverb

cer·​tain·​ly ˈsərt-ᵊn-lē 

1

: in a manner that is certain : for certain

the only event of which anything is certainly known

2

: without doubt : surely

certainly you can do it