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.
According to his official biography, he even served as an intern in the Chicago mayor’s office, certainly a deep dive into a singular iteration of U.S. politics.
From Los Angeles Times • Apr. 14, 2026
Listening intently, Barr seemed to understand both the truth and that telling it to the president would almost certainly cost him his job.
From Salon • Apr. 14, 2026
“Well the break below $77 has lasted all of two days, and with it firmly back above that level on heavy volume, we certainly would not want to stay short the group right now.”
From Barron's • Apr. 13, 2026
“It’s certainly well within the capacity of the forces that are there to mount a blockade,” said Bryan Clark, a retired naval officer and senior researcher at the Hudson Institute.
From The Wall Street Journal • Apr. 12, 2026
“You could certainly bring up your ideas with the lead teachers if you have some,” Dad tells Celia, even though the conversation has long since departed that station.
From "Keeping Pace" by Laurie Morrison
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.
