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

And even if history had not seen this before, this generation certainly has. —Leonard Pitts Jr, Miami Herald, 1 Jan. 2026

Then [there were] significant changes, certainly with the Goodbye Yellow Brick Road. —Angela Andaloro, PEOPLE, 1 Jan. 2026

His new control over his powers is certainly on display. —Maggie Fremont, Vulture, 1 Jan. 2026

Income inequality levels and the racial wealth gap will almost certainly persist, especially for those without generational wealth. —Essence, 1 Jan. 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