certainly

adverb

cer·​tain·​ly ˈsər-tᵊn-lē How to pronounce certainly (audio)
Synonyms of certainly
1
: in a manner that is certain : with certainty
2
: it is certain that : assuredly

Synonyms of certainly

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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.
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Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Still, the emotionally stunted John claims not to harbor ill feelings toward Hal, though this is most certainly challenged by the end of the episode. — Siddhant Adlakha, Vulture, 31 Aug. 2026 Teoscar Hernández, who had been slumping, hit a two-run home run, and consecutive run-scoring wild pitches from Tigers reliever Tanner Rainey certainly helped. — Katie Woo, New York Times, 31 Aug. 2026 Attackers have never respected those organizational boundaries, and AI certainly will not. — Emil Sayegh, Forbes.com, 30 Aug. 2026 There, the president’s order and the post office rule enforcing it will certainly be opposed by the Court’s three liberal justices, who disagreed with the conclusion that opponents had filed their case too soon. — Sharon Bernstein, Sacbee.com, 30 Aug. 2026 See All Example Sentences for certainly

Word History

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of certainly was in the 14th century

Phrases Containing certainly

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certain
certainly
certainly not
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Cite this Entry

“Certainly.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/certainly. Accessed 1 Sep. 2026.

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Kids Definition

certainly

adverb
cer·​tain·​ly ˈsərt-ᵊn-lē How to pronounce certainly (audio)
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
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