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

There's one Panama fan here that certainly knows about an important finish. — Nbc News, NBC news, 28 June 2026

The Patriots certainly have one of their best group of receivers, led by Paul Turner, who has speed and big-play ability. — Eric Sondheimer, Los Angeles Times, 28 June 2026

Teams with four points — a win, a draw and a loss — almost certainly will make the round of 32. — ABC News, 27 June 2026

And so that certainly was the case (Friday) in a way. — Meghan Montemurro, Chicago Tribune, 27 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