This is the 1217th most frequent Polish word.
maciej
"Maciej" is a Polish male given name, equivalent to "Matthias" or "Matthew" in English.
Here, 'Maciej' is used as a proper noun referring to a person's name.
Maciej jest na mojej liście zaproszonych gości.
Maciej is on my list of invited guests.
In this sentence, 'Macieja' is the genitive form of 'Maciej,' used to express possession or authorship.
Przeczytałem książkę autorstwa Macieja.
I read a book authored by Maciej.
The word 'Maciej' is used as the subject of the sentence, referring again to the person named Maciej.