Quantcast
Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Scrabble
  • Spanish Central
  • Learner's Dictionary

day one

noun, often capitalized D&O

Simple Definition of day one

  • : the first day or very beginning of something

Source: Merriam-Webster's Learner's Dictionary

Full Definition of day one

  1. :  the first day or very beginning of something

Examples of day one in a sentence

  1. We've known this about the project since Day One.

  2. <since day one of this project, we've always insisted that we would create the best product possible without any consideration of cost>



1971

First Known Use of day one

1971


Learn More about day one


Seen and Heard

What made you want to look up day one? Please tell us where you read or heard it (including the quote, if possible).

WORD OF THE DAY

prophetic or oracular

Get Word of the Day daily email!

WORD GAMES

Take a 3-minute break and test your skills!

confounded-person

Which is a synonym of indolent?

philistine lazy frenetic melancholy
Name That Thing

Test your visual vocabulary with our 10-question challenge!

TAKE THE QUIZ
SCRABBLE® Sprint

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ