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

Gonzales is certainly a name to watch in Charlotte’s quarterback battle, throwing for 6,682 yards, 51 touchdowns, and 22 interceptions spanning three years at Western Carolina. —Hunter Bailey, Charlotte Observer, 30 Mar. 2026

For families While the friendly staff and spacious rooms are certainly hospitable to families, the overall vibe takes its cues from the neighborhood–chic, cool, and largely for adults. —Condé Nast, Condé Nast Traveler, 30 Mar. 2026

Democrats have a supermajority in the Illinois House and Senate, so passage certainly seems possible. —Jeremy Gorner, Chicago Tribune, 29 Mar. 2026

The stone is believed to repel negativity—a quality handy in any decade, but certainly this one. —Kathryn O’Shea-Evans, Robb Report, 29 Mar. 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