This is the 13230th most frequent Polish word.
opartej
"Based on."
The word 'opartej' is an adjective modifying 'książki' and indicates being derived from 'oparcie', meaning 'to base on'.
Nie mogłem znaleźć książki opartej na rzeczywistych wydarzeniach.
I couldn't find a book based on real events.
Here, 'opartej' describes the type of storage method, derived from 'oparcie' which implies reliance upon.
W bazie danych przechowywanie jest opartej na chmurze.
In the database, storage is based on the cloud.
In this sentence, 'opartej' qualifies the model described, referring to its basing upon the experimental results.