This is the 6997th most frequent Polish word.
grzegorz
"Grzegorz" is the Polish form of the name "Gregory."
Here, 'Grzegorz' is a proper noun used as a subject in the sentence to refer to a specific person.
Grzegorz jest moim przyjacielem.
Grzegorz is my friend.
In this sentence, 'Grzegorzem' is the instrumental case of the proper noun 'Grzegorz', illustrating Polish case usage in communication contexts.
Rozmawiałem z Grzegorzem wczoraj.
I talked to Grzegorz yesterday.
Here, 'Grzegorza' is the accusative case of the proper noun 'Grzegorz', showing a direct object in the sentence.