This is the 2094th most frequent Polish word.
niedzielnym
"Related to Sunday" or "Sunday's."
The word 'niedzielnym' is an adjective; it describes the noun 'wydaniu' (edition) and indicates that the edition is related to Sunday.
W niedzielnym wydaniu gazety znajdziesz przewodnik po mieście.
In the Sunday edition of the newspaper, you will find a city guide.
The word 'niedzielnym' is used as an adjective here, modifying the noun 'obiedzie' (lunch) to specify that the lunch takes place on Sunday.
Spotkamy się na niedzielnym obiedzie w restauracji.
We will meet at the Sunday lunch in the restaurant.
Here, 'niedzielnym' modifies the noun 'spacerze' (walk), denoting that this specific walk happened on a Sunday.