Jamtlandic or Jamtish (jamska, formally a definite form, in Jamtlandic) is a well-defined group of dialects of Scandinavia. It is spoken in the Swedish province of Jämtland. It is commonly used in the region between the modern Swedish-Norwegian border in the west and the pre-1645 Swedish-Norwegian border in the east, though Trøndersk is spoken in Frostviken in the northernmost part of Jämtland colonized in the 18th century by Norwegians, and Norrlandic is spoken in Ragunda in the easternmost part of Jämtland which until 13th century was a part of Ångermanland.
Jamtlandic shares many characteristics with both Trøndersk—the dialect spoken in Trøndelag, Norway—and with the dialects spoken along the coast of Norrland, Sweden. Due to this ambiguous position, there has been a debate since the early 20th century whether Jamtlandic belongs to the West Norse or the East Norse language group. Jamtlandic cannot be uniquely defined belonging to either of these groups. Prior to, and around, the time of the dissolution of the Swedish-Norwegian union, Jamtlandic was undisputedly considered a dialect of Norwegian. See, e.g., p. 112 in part one of Adolf Noreen's Vårt språk (translated from Swedish):
- The Westnorthern Swedish ("Norwegian-Swedish"), originally Norwegian dialects in Särna and Idre (the northwesternmost Dalarna), Härjedalen and Jämtland (where, though, the language east of Östersund eventually passes into Medelpadian or Ångermanlandic).