day one

noun, often capitalized D&O

Definition of day one

: the first day or very beginning of something

Keep scrolling for more

Examples of day one in a Sentence

We've known this about the project since Day One. since day one of this project, we've always insisted that we would create the best product possible without any consideration of cost

Recent Examples on the Web

With Fallout 76, Bethesda’s undoubtedly counting on the diehard fans buying the game on day one, Steam or no Steam. Hayden Dingman, PCWorld, "Fallout 76 abandons Steam for Bethesda's own launcher," 7 Aug. 2018 That includes Dott Bradley, who's been part of the cast from day one. CBS News, "Harper Lee's hometown performs community production of "To Kill a Mockingbird"," 8 June 2019 The most rewarding part of running restaurants is… seeing my staff that have been with me from day one grow each day. Kristin Braswell, Bon Appétit, "New Orleans Chef Nina Compton Isn't Afraid of the Dish Pit," 7 June 2019 In this market, buyers are going up against multiple offers day one. Michigan Schools & Government Credit Union, Detroit Free Press, "8 myths of modern mortgages every home buyer should know," 7 June 2019 Harris is proposing a $6,000 tax credit for families earning less than $100,000 a year and to repeal the Trump tax cuts on day one of her administration. Howard Koplowitz |,, "Kamala Harris in Alabama: ‘Legitimate fear’ that women will die from abortion ban," 7 June 2019 BACKGRIDXPOS May 27, 2018 Pippa attended day one of the French Open with her husband, James Matthews. Marina Liao, Marie Claire, "Pippa Middleton's Love for Wrap Dresses Goes All the Way Back to 2007," 27 Aug. 2018 So which younger players seemed to stand out as the Hurricanes made the shift from offseason conditioning to day one on the field? Christy Cabrera Chirinos,, "N'Kosi Perry, Lorenzo Lingard among young Hurricanes off to solid spring start," 21 Mar. 2018 Some of these tweets are from as early as 2012—further proving that Blake has been wagging his finger since day one. Kelly O'sullivan, Country Living, "‘The Voice’ Coach Blake Shelton Has a Quirky Habit That Everyone's Talking About," 5 Mar. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'day one.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

See More

First Known Use of day one

1971, in the meaning defined above

Keep scrolling for more

Learn More about day one

Statistics for day one

Last Updated

16 Jul 2019

Look-up Popularity

Time Traveler for day one

The first known use of day one was in 1971

See more words from the same year

Keep scrolling for more

More Definitions for day one

day one


English Language Learners Definition of day one

: the first day or very beginning of something

More from Merriam-Webster on day one

Thesaurus: All synonyms and antonyms for day one

Comments on day one

What made you want to look up day one? Please tell us where you read or heard it (including the quote, if possible).


food or victuals

Get Word of the Day daily email!

Test Your Vocabulary

Farm Idioms Quiz

  • cow coming home
  • What does 'poke' refer to in the expression 'pig in a poke'?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!