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 Brown’s wife and kids helped out from day one and now his grandchildren and nieces and nephews help out, too, along with the community. Linda McIntosh, San Diego Union-Tribune, 18 Apr. 2024 On day one, Haldane and Case had sat upright inside the largest chamber and breathed oxygen and played the ball game at shallower depths, with both subjects developing no more than a mysterious slight cough afterward. Rachel Lance, Smithsonian Magazine, 16 Apr. 2024 See all Example Sentences for day one 

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'day one.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1971, in the meaning defined above

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

Dictionary Entries Near day one

Cite this Entry

“Day one.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/day%20one. Accessed 4 May. 2024.

Last Updated: - Updated example sentences
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