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

An arrivals-and-departures board in the cell phone area would certainly help. —Sun Sentinel Editorial Board, Sun Sentinel, 17 May 2026

But your profile is almost certainly there, and Google is ranking it. —Kurt Knutsson, FOXNews.com, 16 May 2026

The domestic credentials are certainly strong. —Andreas Wiseman, Deadline, 16 May 2026

Modern superstars certainly seem much more accessible than Jackson ever did, because of social media and the demand from fans and business partners for more visibility. —Jemele Hill, The Atlantic, 16 May 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