This is the 132nd most frequent Polish word.
poniedziałek
"Poniedziałek" means "Monday" in English.
Here, 'poniedziałek' refers to a specific day of the week as a point in the schedule.
W poniedziałek będziemy mieli spotkanie.
On Monday, we will have a meeting.
Here, 'poniedziałek' is utilized in the nominative singular form to state a general fact.
Poniedziałek jest pierwszym dniem roboczym.
Monday is the first day of the workweek.
In this sentence, 'Poniedziałków' (genitive plural form) highlights the concept of all Mondays.