day one noun
or Day One
or Day One
Learner's definition of DAY ONE
[singular]
: the first day or very beginning of something第一天 -
We've known this about the project since/from Day One.从项目开始的第一天起我们就了解这个情况。
-
The new governor will start implementing these changes on day one. [=the first day of the governor's term]新州长将在他上任的第一天开始实施这些变更。