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.
Earn another point and Scotland would almost certainly make it out of the groups for the first time, with Morocco back here on Friday offering a chance of just that.
From BBC • Jun. 14, 2026
“The content certainly had a lot of places where it could improve, but it wasn’t horrible,” Uhls said.
From Los Angeles Times • Jun. 12, 2026
And the massive run-up in tech stocks since the end of the first quarter certainly hasn’t helped.
From Barron's • Jun. 12, 2026
“It is certainly hard to believe that little company that started in a warehouse in El Segundo is now going public with the largest IPO ever,” he said Friday.
From The Wall Street Journal • Jun. 12, 2026
The smell— goodness, it certainly doesn’t smell like the hotel in Lucerne.
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.
