This is the 6526th most frequent Polish word.
cymańskiego
"Cymańskiego" is the genitive form of the Polish surname "Cymański," referring to something belonging to or associated with Cymański.
In this sentence, 'Cymański' is used as a possessive noun referring to the person Cymański, emphasizing ownership of the book.
Książka Cymańskiego jest bardzo interesująca.
Cymański's book is very interesting.
Here, 'Cymański' is used as a proper noun, mentioning an individual's name directly.
Widziałem Cymańskiego na wczorajszej konferencji.
I saw Cymański at yesterday's conference.
In this sentence, 'Cymański' denotes the individual whose project is being referred to, showing association with the project.