This is the 3063rd most frequent Polish word.
pomorskim
"Pomorskim" means "Pomeranian" or "of Pomerania," referring to the region in Poland.
Here, "pomorskim" is used as an adjective in the locative case, modifying "województwie" (voivodeship), indicating location.
Mieszkam w województwie pomorskim.
I live in the Pomeranian Voivodeship.
In this sentence, "pomorskim" describes the region, again serving as an adjective in the locative case, indicating location.
Jego dom znajduje się w regionie pomorskim.
His house is located in the Pomeranian region.
Here, "Pomorskim" is the noun form (proper noun) in the locative case, referring to the Pomeranian area.