day one

noun

variants often Day One
Synonyms of day onenext
: 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.
Encryption, strict access controls, medical-grade testing and clear update policies should be baked in from day one. Kurt Knutsson, FOXNews.com, 19 June 2026 Service for Rivian has been a hot topic since day one. Joel Feder, The Drive, 18 June 2026 Moreover, this team designed the material with mass manufacturing in mind from day one. Mrigakshi Dixit, Interesting Engineering, 18 June 2026 Heuermann caved as evidence grew overwhelming, Brown says While the public saw the serial killer from afar, Brown had a rare perspective, having spent countless hours with Heuermann after being assigned to the case on day one. Carolyn Gusoff, CBS News, 18 June 2026 See All Example Sentences for day one

Word History

First Known Use

1953, in the meaning defined above

Time Traveler
The first known use of day one was in 1953

Browse Nearby Words

Cite this Entry

“Day one.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/day%20one. Accessed 22 Jun. 2026.

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