Kainuu.

Unknown. Probably in some way related to Old Norse kvenir and Russian каяний (kajanij), каянский (kajanskij) (whence Kajaani and Swedish Kajanaland). The term has historically been variously applied to different regions in what is now northern Finland and its vicinity. Theories have included: Details * Borrowing from Proto-Norse [script needed] (*gainu, “gully, hole; gap, opening”) (compare Norwegian gein (“corner rope of a seine”)), originally as Finnish kainus, referring to an 'opening' or passage in a waterway, e.g. a river mouth, or a place through which fishermen could sail to reach home. The modern form Kainuu would then be levelled from an inflected stem kainu(h)u-. ** Earlier compared also to dialectal kainus (“central stanchion in a sleigh”), perhaps through a meaning like “messenger's scepter”, perhaps borrowed from the same North Germanic root, but the semantics are rather questionable. * From a word meaning “(humid) lowland”, attested in some older dictionaries as kainu, kaino, perhaps borrowed from Old Norse hvein or earlier Proto-Germanic *hwainō (compare dialectal Swedish hven (“swamp”)). There is no evidence for such a word in Finnish dialects, however. The lack of knowledge of what the term originally meant, even as a place name, has proven an obstacle to attempts to explain it. First attested as part of Old Novgorodian Каꙗно море (Kajano more), [script needed] (Kaino more) in 1323; the sound correspondences between the Finnic, Slavic and North Germanic terms have not been explained. According to Heikkilä (2014), the North Germanic forms would have been reborrowed from Finnic (which in turn would be from the Germanic term for 'opening, passage'), specifically via Proto-Finnic *Kainus > Proto-Germanic *Kwēinulanda (*Kʷàinulanda, whence then Old West Norse Kvēnland); later, it was also incorrectly (folk-etymologically) analyzed as containing kona, kvenn- (“woman”) (leading e.g. to the mistranslated Latin Terra feminarum). He also theorizes that the term originally referred to a place further south, e.g. around modern Satakunta, before it spread/moved north during the Viking Age due to migrations further north. Perhaps the Slavic forms, on the other hand, may have been adopted from such a Latin form as Latin caianus, Caiania (influenced by -ānus), although such a form is not found in the Latin translation of the 1323 Treaty of Nöteborg, the Novgorodian version of which Old Novgorodian Каꙗно море (Kajano more) first appears in.