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

In 2024, there were 58,587 day one early voters in Tarrant County. — Eleanor Dearman, Fort Worth Star-Telegram, 20 Oct. 2026

But regardless, Apple thinks plenty of people will still be lining up at its stores on day one for the first folding phone in its history. — Will McCurdy, PC Magazine, 18 Oct. 2026

What isn’t decided yet is whether AI agents get bolted onto old systems as an afterthought or built in from day one with the same discipline organizations already apply to hiring, managing and governing people. — Ryan Austin, Forbes.com, 16 Oct. 2026

The mayor before that, Bill de Blasio, had pledged to eliminate the rides on day one of his administration but abandoned the crusade after heavy opposition from unions and a media blitz involving actor Liam Neeson. — Anthony Izaguirre, Los Angeles Times, 14 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