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Synonyms

certainly

American  
[sur-tn-lee] / ˈsɜr tn li /

adverb

  1. with certainty; without doubt; assuredly.

    I'll certainly be there.

  2. yes, of course.

    Certainly, take the keys.

  3. to be sure; surely.

    He certainly is successful.


certainly British  
/ ˈsɜːtənlɪ /

adverb

  1. with certainty; without doubt

    he certainly rides very well

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

  1. by all means; definitely: used in answer to questions

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of certainly

First recorded in 1250–1300; Middle English; certain + -ly

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.”

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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.

See Examples For:

It will certainly defy the odds and expectations, but I feel it might be just a very entertaining ride as Hull City try.

From BBC Aug. 19, 2026

“There’s certainly value there,” said Jamie Meyers, an analyst at Laffer Tengler Investments.

From MarketWatch Aug. 19, 2026

College coaches came through the spring evaluation period and certainly took notice of Kirkpatrick, who plays at a school where Chargers linebacker Daiyan Henley and former USC linebacker Hayes Pullard once gained attention.

From Los Angeles Times Aug. 17, 2026

And Thatcher’s other film roles in 2023’s “The Boogeyman” and a bit part in the following year’s “MaXXXine” certainly don’t help Hollywood’s perception of her as a wannabe scream queen.

From Salon Aug. 17, 2026

People often said that the king loved gold more than anything, but certainly not more than his own son, his heir.

From "Rump: The (Fairly) True Story of Rumpelstilskin" by Liesl Shurtliff

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