This is the 12674th most frequent Polish word.
niedzielê
The Polish word "niedzielę" means "Sunday" (accusative or instrumental case).
The word "niedzielę" is used here in the accusative case to denote time (Sunday), indicating the time of an action.
W niedzielę idziemy do kina.
On Sunday, we are going to the cinema.
In this sentence, "niedzielę" also appears in the accusative case, as the object receiving the action of spending.
Niedzielę spędziłem z rodziną.
I spent Sunday with my family.
Here, "niedzielę" functions as the direct object of the verb "pamiętam", thus taking the accusative form.