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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

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.