day one

noun

variants often Day One

: the first day or very beginning of something

Synonyms of day one

• beginning
• start
• inception
• commencement
• alpha
• onset
• launch

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

The Orioles started the day one game out but tied with the Twins behind three teams. — ABC News, 23 Aug. 2026

The author advises negotiating exit terms fiercely, choosing fewer, aligned investors, and building sellable systems from day one, whether or not outside capital is involved. — Lien De Pau, Forbes.com, 21 Aug. 2026

On day one, he was recognised multiple times by fans, in spite of being an almost unknown quantity barely a week before. — Chris Waugh, New York Times, 21 Aug. 2026

By listing in the MLS on day one, sellers gain more visibility and more opportunities to close with the best deal right from the start. — Kansas City Star, 21 Aug. 2026

Word History

First Known Use

1953, in the meaning defined above

Rhymes for day one

• begun
• grandson
• gudrun
• handgun
• homespun
• outdone
• outrun
• pashtun
• redone
• rerun
• shotgun
• someone