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 Amazon, maybe not on day one but certainly early on, had a viable profit formula inside the business. —Rory McDonald, Fortune, 6 June 2026

That was certainly the case recently with his latest blockbuster, Iceman, which generated more than 462 million streams of its 18 tunes – and that was only one of his three full-lengths. —Hugh McIntyre, Forbes.com, 6 June 2026

Ripa, 55, is certainly enjoying watching from the sidelines. —Dave Quinn, PEOPLE, 6 June 2026

But weapons are almost certainly still getting through. —Mick Krever, CNN Money, 6 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