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

Guadagnino speaks in calligraphy; adjectives almost certainly accompany a proper name — the extraordinary, the wonderful, the genius. — E. Alex Jung, Vulture, 2 Oct. 2026

Not that this strictly counts as stand-up comedy, but certainly a lot of it is in that sphere or involves those skills. — Chris Willman, Variety, 1 Oct. 2026

But even if Waldron’s disposition does not give off Master of the Universe vibes, his resumé certainly does. — Morgan Chittum, Fortune, 1 Oct. 2026

The decline of the conference, in terms of NCAA bids, has certainly been beeping on UConn’s radar, even though both programs have had enormous success in the 2020s. — Dom Amore, Hartford Courant, 1 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