This is the 8240th most frequent Polish word.
ostrowskiej
"Ostrowskiej" is the genitive or locative form of "Ostrowska," typically meaning "of Ostrowska" or "related to Ostrowska," a Polish surname or place name.
The word 'ostrowskiej' here is an adjective derived from a proper noun Ostrowska.
Wczoraj poszliśmy na koncert muzyki ostrowskiej.
Yesterday, we went to a concert of Ostrowska music.
In this sentence, 'ostrowskiej' contextualizes the noun 'kobiety' indicating possession or relation.
Czy przypadkiem widziałeś książkę ostrowskiej kobiety?
Have you accidentally seen the book of the Ostrowska woman?
'Ostrowskiej' modifies 'artystki,' signifying the origin or association of the artist.