adverb
Etymology
Origin of certainly
Explanation
Use the adverb certainly when you’re sure about a particular action — absolutely, positively sure. If you love the new shoes you just bought, you may defend your purchase by saying they were certainly worth the money you paid. The word certainly emphasizes that you’re positive about something. When you hear thunder and look up at a gray sky, you might say it will certainly rain. If you’re on a diet, you could say that you will certainly avoid chocolate cake. Certainly can also be used to answer a question in the affirmative. If your boss asks to speak to you, you might answer, “Certainly.” It’s just a formal way of saying “yes.”
Vocabulary lists containing certainly
Florida's B.E.S.T. Common Suffixes: -ly
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"Alice's Adventures in Wonderland" by Lewis Carroll, Chapters 4–6
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Novel Study: Barrio Boy, Parts 1–3
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
"It's really hard to digest the idea. I certainly don't consider myself in that rarified air of some of the writers, but if you wanna be in that club, I'm there."
From Barron's • Jun. 11, 2026
"And certainly over the last few weeks and months we've actually seen a spike to that."
From BBC • Jun. 11, 2026
Still, the model certainly seems to be a more helpful way of thinking about bitcoin than competing models — some of which have predicted bitcoin would reach $1 million.
From MarketWatch • Jun. 11, 2026
No national team from outside Europe or South America has ever hoisted the World Cup, and while that will certainly change someday, it won’t be this year.
From Salon • Jun. 11, 2026
“I certainly didn’t know then that I liked you.”
From "The Bletchley Riddle" by Ruta Sepetys and Steve Sheinkin
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
