This is the 6692nd most frequent Swedish word.
måndagen
"The Monday."
Here, "måndagen" specifies the particular Monday on which the meeting occurs.
Vi träffas på måndagen för att diskutera projektet.
We meet on Monday to discuss the project.
In this usage, "måndagen" is the subject of the sentence, referring to the past Monday for comparison.
Måndagen var inte lika hektisk som fredagen.
Monday was not as hectic as Friday.
Here, "måndagen" refers to a specific upcoming Monday within the context of future planning.