This is the 3372nd most frequent Polish word.
wspomnianej
"Mentioned"
Here, 'wspomnianej' (the mentioned) serves as an adjective modifying the noun 'książki' (book) in the genitive case.
Wspomnianej książki nie udało mi się znaleźć w bibliotece.
I couldn't find the mentioned book in the library.
In this sentence, 'wspomnianej' modifies the noun 'sprawy' (case) in the genitive case due to its contextual placement.
Proszę o wysłanie mi szczegółów wspomnianej sprawy.
Please send me details of the mentioned case.
Here, the word 'wspomnianej' modifies 'osoby' (person) in the genitive case, referring to a referenced individual.