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

But Swiss coach Murat Yakin certainly isn’t taking anything for granted. —Joseph Dycus, Mercury News, 13 June 2026

Musk is certainly not alone in seeing a financial windfall from SpaceX’s IPO. —Jordan Novet,lora Kolodny, CNBC, 13 June 2026

The apology was certainly warranted, given the Seleção’s biggest loss to Argentina since 1964, which ultimately cost Dorival Júnior his job and accelerated the arrival of former Real Madrid boss Ancelotti. —Emile Nuh, CNN Money, 13 June 2026

Carrie Bradshaw would certainly approve. —Meg Walters, InStyle, 13 June 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