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

Due to their fragility, the trumpets will now almost certainly never be played again. — Sheena McKenzie, CNN Money, 10 Aug. 2026

There’s certainly no route back to a more moderate form of leadership. — Jennifer Maas, Variety, 10 Aug. 2026

Sunday night’s brutal, devastating episode of House of the Dragon certainly made that point abundantly clear. — Erik Kain, Forbes.com, 10 Aug. 2026

Chai Épicé is certainly fitting for fall with its sexy, woodsy scent. — Alyssa Morin, InStyle, 9 Aug. 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