DAY ONE Synonyms: 68 Similar and Opposite Words

day one

noun

Definition of day one

as in beginning

the point at which something begins since day one of this project, we've always insisted that we would create the best product possible without any consideration of cost

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms

Example Sentences

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.

Recent Examples of day one By noon on day one, more than 3,000 ballots had already been cast. — Leondra Head, CBS News, 13 Oct. 2026 Benski’s own investment vehicle, TBI, has been a major shareholder since day one. — Jesse Whittock, Deadline, 12 Oct. 2026 Fans who’ve followed this story from day one would probably still welcome a refresher. — Angie Han, HollywoodReporter, 12 Oct. 2026 Over-harvesting the donor area to achieve maximum density on day one can leave nothing for the repair that later progression demands. — William Jones, Miami Herald, 12 Oct. 2026 See All Example Sentences for day one

Recent Examples of Synonyms for day one

Noun

So, Ohtani kept trying to work his way back to the mound for weeks after receiving a lubricating Orthovisc injection in his knee at the beginning of the All-Star break.

— Maddie Lee, Los Angeles Times, 14 Oct. 2026
The October introduction marks the beginning of a broader evolution for Lune+Aster, with additional innovation planned across complexion, eye and lip categories through 2027.

— Kathryn Hopkins, Footwear News, 13 Oct. 2026

Definition of beginning

Noun

In neighboring Massachusetts, positive alpha-gal tests have increased substantially on Martha’s Vineyard.

— Stephen Underwood, Hartford Courant, 14 Oct. 2026
The results from the EEG session independently confirmed that, with alpha-band activity (normally a marker of the brain gating visual input) reduced by nearly half.

— Jacek Krywko, ArsTechnica, 10 Oct. 2026

Definition of alpha

Noun

But in those who used it more addictively, social reward activity peaked before puberty’s onset.

— Allison Parshall, Scientific American, 20 Oct. 2026
During the experiment, the chip analyzed signals to predict the onset of sawtooth instabilities, which involve rapid changes in plasma conditions.

— Georgina Jedikovska, Interesting Engineering, 19 Oct. 2026

Definition of onset

Noun

Tesla began taking $50,000 reservations—or $250,000 for one of 1,000 limited Founders Series cars—and targeted a 2020 launch.

— Bilin Lin, Fortune, 17 Oct. 2026
The successful launches, as reported by the Russian Defense Ministry, demonstrate the operational use of both missile systems during a single training activity.

— Prabhat Ranjan Mishra, Interesting Engineering, 17 Oct. 2026

Definition of launch

Browse Nearby Words

day nursery

day one

day ones

See all Nearby Words

Cite this Entry

Style

“Day one.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/day%20one. Accessed 20 Oct. 2026.

Copy Citation

Synonyms of day one

noun

Example Sentences

Browse Nearby Words

Cite this Entry

More from Merriam-Webster

Word of the Day

compunction

Popular in Grammar & Usage

Merriam-Webster’s Great Big List of Words You Love to Hate

'Can' vs. 'May'

'Affect' vs. 'Effect'

More Commonly Mispronounced Words

Is it 'nerve-racking' or 'nerve-wracking'?

Popular in Wordplay

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

Did 'orange' the fruit or the color come first?

Even More Bird Names that Sound Like Insults (and Sometimes Are)

12 Lovely and Unusual Words for the Natural World

Popular

Merriam-Webster’s Great Big List of Words You Love to Hate

The Longest Long Words List

9 Words That Sound Like Insults But Aren't

Games & Quizzes