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  1. (used to express complete agreement or strong affirmation): Are you starting your diet tomorrow? Definitely!

Origin of definitely

First recorded in 1575–85; definite + -ly

Synonyms for definitely

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1. See clearly. 2. absolutely, certainly. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for definitely

Contemporary Examples of definitely

Historical Examples of definitely

British Dictionary definitions for definitely


  1. in a definite manner
  2. (sentence modifier) certainlyhe said he was coming, definitely
sentence substitute
  1. unquestionably: used to confirm an assumption by a questioner
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

Word Origin and History for definitely

1580s, from definite + -ly (2). As a colloquial emphatic word, attested by 1931.

Online Etymology Dictionary, © 2010 Douglas Harper