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

The poll found that Democrats are 10% more likely to certainly vote this year than Republicans, which eclipses their two-point edge in 2018. — Jay Stahl, USA Today, 19 July 2026

These programs are laudable, certainly beneficial for some people, but overall are of limited effect even in reducing recidivism, let alone dealing with the conditions that generate criminality in the first place. — Ronald J. Allen, Chicago Tribune, 19 July 2026

One theory is that English and European voices provide an air of authority, even legitimacy, to a sport which, while embraced by millions in America, is still ‘foreign’, certainly when compared to NFL, baseball and basketball. — Nick Miller, New York Times, 18 July 2026

That remains to be seen, but Brady certainly got the first lick in. — Angelique Jackson, Variety, 18 July 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