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

While Spencer Jones is still a work in progress defensively in center, Grisham certainly shouldn’t be patrolling the position for the Yankees moving forward. — Gary Phillips, New York Daily News, 9 Oct. 2026

Next-level attentiveness from friendly staff certainly helps. — Condé Nast, Condé Nast Traveler, 8 Oct. 2026

When a hurricane comes barreling through Florida, there certainly will be winners and losers. — James Coffin, The Orlando Sentinel, 8 Oct. 2026

If there is any place that would be off-limits to AI, the control room of a nuclear power plant certainly sounds like one. — Andrew Moseman, IEEE Spectrum, 8 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