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

Supporters certainly want to see it, with a strong sense in the stands that he’s been held back more often than set free. —Gregg Evans, New York Times, 23 Feb. 2026

Hotel staff will almost certainly point out the 16-storey-high, 250-panel-long mural in the atrium, ‘The Great Motherland of China’, rumoured to be the work of 40 artists and the largest Chinese silk painting in the world. —Condé Nast, Condé Nast Traveler, 22 Feb. 2026

Colorado is rich in mountain towns and ski towns, but Breckenridge is certainly one of its finest examples of both. —Lydia Mansel, Travel + Leisure, 22 Feb. 2026

The biggest name associated with the film is certainly its producer, the Hindi film star Farhan Akhtar, who will portray Ravi Shankar in Sam Mendes’ upcoming Beatles films. —Andreas Wiseman, Deadline, 22 Feb. 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