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
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
"Alice's Adventures in Wonderland" by Lewis Carroll, Chapters 4–6
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Novel Study: Barrio Boy, Parts 1–3
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
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.
Coach Lincoln Riley certainly knows USC well enough now to understand his time to deliver is running out.
From Los Angeles Times ● Sep. 2, 2026
Fery's career is certainly unrecognisable compared to where it was.
From BBC ● Sep. 1, 2026
"It's not binding, but it's certainly something that I'm sure the Vermont judge will look at," said Gerrard.
From Barron's ● Sep. 1, 2026
“We certainly have regular return clients each year,” said Kingsley Read, director at ShipMyCar, a U.K.-based logistics company that handles car imports.
From The Wall Street Journal ● Sep. 1, 2026
Almost certainly not an ideal day for London.
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.
