This is the 6548th most frequent Polish word.
czwartkowa
"Thursday's" or "related to Thursday."
The word 'czwartkowa' is an adjective describing 'gazeta' (newspaper), indicating that the newspaper is associated with Thursday.
Czwartkowa gazeta leżała na stole.
The Thursday newspaper was lying on the table.
Here, 'czwartkowego' is the genitive form of the adjective 'czwartkowa', modifying 'zebrania' (meeting), showing possession or association with Thursday.
Plan czwartkowego zebrania został zatwierdzony.
The plan of Thursday's meeting was approved.
In this example, 'czwartkowa' is an adjective describing 'podróż' (trip), specifying that the trip took place on Thursday.