certainly

adverb

cer·​tain·​ly ˈsər-tᵊn-lē 

1

: in a manner that is certain : with certainty

2

: it is certain that : assuredly

Synonyms

• all right
• alright
• assuredly
• clearly
• definitely
• doubtless
• easily
• forsooth
• hands down
• inarguably
• incontestably
• incontrovertibly
• indeed
• indisputably
• plainly
• really
• so
• sure
• surely
• truly
• unarguably
• undeniably
• undoubtedly
• unquestionably

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 voice behind all of the above titles is certainly recognizable in Étoile. —Judy Berman, Time, 23 Apr. 2025

This digging did not start, but was certainly accelerated by the U.S. decision to cut 83 percent of all foreign assistance programs. —Ross Rosenfeld, MSNBC Newsweek, 23 Apr. 2025

Natural disasters such as wildfires, hurricanes, earthquakes and tornadoes can certainly be difficult life-altering events. —Daryl Austin, USA Today, 23 Apr. 2025

Keynotes always make new technology sound impressive, and Google’s demos have certainly set high expectations. —Melody Brue, Forbes.com, 23 Apr. 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