or Cassubian is one of the Lechitic languages,
which are a group of Slavic languages.
It is assumed that it evolved from the language spoken by some tribes of
Pomeranians called Kashubians, in the region of Pomerania on the southern
coast of the Baltic Sea between the Vistula and Oder rivers.
It is closely related to Slovincian, and both of them are Pomeranian
language dialects. Many Polish linguists still call it a dialect of Polish.