This is the 8671st most frequent Polish word.
radomiaka
"Radomiaka" refers to something or someone related to Radomiak, a football club based in Radom, Poland.
Here, 'Radomiaka' refers to a male supporter of the Radomiak Radom sports team, emphasizing a person associated with the team.
Radomiaka widziałem w parku, gdy biegał.
I saw a Radomiak in the park, running.
In this usage, 'Radomiaka' indicates possession, referring to the sports team, Radomiak Radom, and its characteristic colors of its shirt.
Koszulka Radomiaka jest zielona i biała.
Radomiak's shirt is green and white.
Here, 'Radomiaka' is used to describe a fan or supporter of the Radomiak Radom team who is present at the stadium.