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

In China, anyone who holds a position of authority is almost certainly a party member, and being kicked out of the party means the end of one’s political career. — Sylvie Zhuang, CNN Money, 16 Aug. 2026

That is unheard-of with prolonged exposure, cognitive processing, and certainly SSRIs, the current standard-of-care options. — Anderson Cooper, CBS News, 16 Aug. 2026

Running out of driving range would certainly be inconvenient. — Kurt Knutsson, FOXNews.com, 16 Aug. 2026

Once approved, residents within the Firewise Community area may be eligible for insurance discounts and certainly become more aware of how to prepare for a wildfire. — Chuck Page, Mercury News, 16 Aug. 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