This is the 8386th most frequent Polish word.
piątkowi
The Polish word "piątkowi" is the dative form of "piątkowy," meaning "related to Friday" or "Friday's."
Indicates time during the day 'piątek' (Friday) in instrumental case to associate it with 'evening'.
W piątkowi wieczór planujemy spotkanie.
On Friday evening, we are planning a meeting.
Here 'piątkowi' is an adjective referring to the evening of Friday, in its instrumental form.
Każdy piątkowi wieczór spędzamy na czytaniu książek.
Every Friday evening, we spend reading books.
It refers to players associated with 'Friday', used here to denote the group linked to Friday.