day one

noun

often capitalized D&O
: the first day or very beginning of something

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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Together, Sinner and Alcaraz had won the past six Grand Slams, and that day one of them would win the seventh. Louisa Thomas, New Yorker, 14 July 2025 Being selected 23rd overall by the Green Bay Packers, the exception is that Golden will go out there and contribute from day one. Steve Bradshaw, Forbes.com, 14 July 2025 The league could learn from what didn’t work to put on a better day one experience in 2026. The Athletic Nhl Staff, New York Times, 12 July 2025 Charles Barkley played the opening round of his life on day one of the American Century Championship. Ben Verbrugge, MSNBC Newsweek, 12 July 2025 See All Example Sentences for day one

Word History

First Known Use

1971, in the meaning defined above

Time Traveler
The first known use of day one was in 1971

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Cite this Entry

“Day one.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/day%20one. Accessed 21 Jul. 2025.

Last Updated: - Updated example sentences
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