This is the 10294th most frequent Polish word.
chełmińskim
"Chełmińskim" means "related to Chełmno," a town in Poland.
Here, 'chełmińskim' functions as an adjective describing the region.
Mieszkam w regionie chełmińskim.
I live in the Chełmiński region.
In this case, 'chełmińskim' denotes a stylistic adjective derived from Chełmno as a proper noun.
Chełmińskim stylem charakteryzują się lokalne budowle.
Local constructions are characterized by the Chełmiński style.
'chełmińskim' is used to describe the distinctive monuments originating from the Chełmno region.