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 67th Fort Lauderdale International Boat Show opened Wednesday across six waterfront venues, welcoming thousands of visitors for day one of what is billed as the world’s largest in-water boat exhibition. — Mike Stocker, Sun Sentinel, 29 Oct. 2026

The people who thrive after a move aren’t necessarily the ones most excited on day one. — Kristin Stoller, Fortune, 26 Oct. 2026

Operators fed Maven intelligence classifying the elementary school as an Iranian military facility, and the system, in turn, marked it as one of the priority targets for day one of the war. — Kylie Jones, Vox, 25 Oct. 2026

Rafael Cabral totaled two saves for Real Salt Lake (11-14-6), which began the day one spot away from a postseason berth in the Western Conference. — ABC News, 24 Oct. 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