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.
One of our testers has been using the vacuum since the end of 2023 and says the suction is just as strong as day one. Toni Sutton, PEOPLE, 7 Oct. 2025 Many are entering the workforce burdened with debt and without the tools to contribute from day one. Sasha Rogelberg, Fortune, 7 Oct. 2025 The gracious donation was a moment that perfectly embodied the festival’s mission of giving back to the same city that’s been showing Clipse love since day one. Amber Corrine, VIBE.com, 6 Oct. 2025 From day one, the Arlington community has embraced Smoke’N Ash with open arms—and open appetites. Alexandra Emanuelli, Southern Living, 6 Oct. 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

Browse Nearby Words

Cite this Entry

“Day one.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/day%20one. Accessed 8 Oct. 2025.

Last Updated: - Updated example sentences
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