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

Training Can’t Keep Pace With Headcount Every new hire arrives with a different level of training, judgment and ethics, and none of that shows up on day one. — Trent Challis, Forbes.com, 23 Sep. 2026

My background has prepared me to hit the ground running and get to work for District 3 on day one. — Miami Herald Staff, Miami Herald, 23 Sep. 2026

Driverless ride-hailing will be part of how people move around, and the question that matters over the next several years isn't whether Tesla's first two-seater was ready for prime time on day one. — Michael Khouw, CNBC, 23 Sep. 2026

Perhaps more unusually at this price, the firmware is open source, with JetKVM saying its new ESP32 firmware will be available from day one. — New Atlas, 18 Sep. 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