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 Russian star, who is set to become a free agent in July, would like to return to the Penguins for a 21st and almost certainly final season. —CBS News, 2 May 2026

Jensen’s at-bat was certainly emblematic of a good baseball team. —Jaylon Thompson may 2, Kansas City Star, 2 May 2026

This is certainly a positive day for those who are working or doing anything to boost their health. —Georgia Nicols, Denver Post, 2 May 2026

Since that request was almost certainly denied, Matsui will either be joining the Padres or be released. —Kevin Acee, San Diego Union-Tribune, 2 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