This is the 4534th most frequent Dutch word.
dag
"Day" or "hello/goodbye."
Here 'dag' means 'day', representing a unit of time in the scope of a 24-hour period.
De dag begint met een prachtige zonsopgang.
The day begins with a beautiful sunrise.
In this context, 'dag' is used as an informal and colloquial way to say goodbye.
Hij zei dag en liep snel weg.
He said goodbye and quickly walked away.
In this sentence, 'dag' is used as a greeting, functioning similarly to saying 'hello'.