This is the 11103rd most frequent Russian word.
гомельском
The word "гомельском" is the prepositional case of "гомельский," which means "of Gomel" or "relating to Gomel," a city in Belarus.
The word "гомельском" is an adjective derived from "Гомель," the name of a city, and it modifies "университете" to specify the location of the university.
Я учился в Гомельском университете.
I studied at the Gomel university.
Here, "гомельском" modifies "районе," referring to the specific district associated with Gomel.
Они провели исследование в Гомельском районе.
They conducted research in the Gomel district.
In this sentence, "гомельском" describes "муниципалитете," specifying the municipality related to Gomel.