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

The company has certainly taken on a lot of debt and lease commitments. — Jim Edwards, Fortune, 16 Oct. 2026

And certainly Mossy Horns was way ahead of the next buck on the nontypical whitetail list, shot in British Columbia in 1905 and scoring 245-7/8. — Al Dawson, Outdoor Life, 15 Oct. 2026

Their courtroom victory in January 1856 led to one of the largest legal emancipations in US history, and certainly the largest anywhere west of Texas. — Literary Hub, 15 Oct. 2026

Pomeroy’s team believes a rounded spear carved from wood almost certainly caused the killing blow. — Andrew Paul, Popular Science, 15 Oct. 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