Old English finnas, from Old Norse finnr, the Norsemen's name for the Suomi. Some suggest a connection with fen. Attested in Tacitus as Fenni. Finlander in English is from 1727.[Finn etymology, Finn origin, 英语词源]
early 15c., "skin or fur of the mink," from a Scandinavian source (compare Swedish menk "a stinking animal in Finland"). Applied in English to the animal itself from 1620s.