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

Yes, a case certainly could be made for the Heat winning the summer. — Ira Winderman, Sun Sentinel, 6 Sep. 2026

The siblings have certainly seen recent success through their family investment firm RAJ Sports. — Sasha Rogelberg, Fortune, 6 Sep. 2026

Too well stocked, according to some, but surely options are what will be needed throughout a long season, and certainly what Enzo Maresca had been crying out for all summer. — Sam Lee, New York Times, 6 Sep. 2026

Father Joe himself certainly has the backstory for it, being a war veteran who married an Asian woman who died young and lost his grieving daughter to an overdose. — Damon Wise, Deadline, 6 Sep. 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