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

Wilder things certainly have happened in the MLB offseason, and the winter meetings haven’t even started yet. —Ryan Gaydos, FOXNews.com, 13 Nov. 2025

Imagination is certainly a powerful tool in and of itself, but without real-life experiences to draw from, characters and stories themselves are far less likely to be portrayed in an authentic way that appeals to a mass audience. —Wyles Daniel, USA Today, 12 Nov. 2025

Furthermore, direct $2,000 payments would almost certainly have to be approved by Congress and not done by executive fiat, according to York. —Zach Halaschak, The Washington Examiner, 12 Nov. 2025

There’s certainly competition for Agency—agentic AI for customer service has been a hot area, featuring ascendant companies like Sierra and Decagon. —Allie Garfinkle, Fortune, 12 Nov. 2025

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