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

Crumbl certainly captured the attention of Gen Z in 2025, inspiring its own review trend on TikTok earlier this year, where avid customers would pick up the weekly assortment of cookies and rate them out of 10. —Kaleigh Werner, Footwear News, 10 Dec. 2025

The last Fed decision of the year Markets are betting the central bank will almost certainly cut rates by a quarter point Wednesday, and those hopes have helped stock markets climb back toward record highs. —Kavitha Shastry, CNBC, 10 Dec. 2025

But there is almost certainly some bias at play. —Phil Wahba, Fortune, 10 Dec. 2025

And Heuer certainly has neighbors who think the whole thing has been blown out of proportion. —Théoden Janes, Charlotte Observer, 10 Dec. 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