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

That said, Chelsea did remain competitive and relatively organised, certainly more so than in many of the other games this season in which they have been reduced to 10 men. —Cerys Jones, New York Times, 25 Apr. 2026

As hotel manager Jaime jokes, visitors come to Manhattan to be everywhere but their room, though the airy, spacious room is most certainly a nice plus. —Condé Nast, Condé Nast Traveler, 25 Apr. 2026

Polyamory is nothing new in California, and certainly not in Oakland, which in 2024 became the first city in the state to outlaw discrimination based on family structure — a move meant in part to protect multiple partners’ rights to manage a medical emergency in the hospital. —Sonja Sharp, Los Angeles Times, 25 Apr. 2026

Boasting 37 miles of pure electric power, the NX450h+ certainly succeeds for consumers looking to float around town. —Marc D Grasso, Hartford Courant, 25 Apr. 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