The name Suomi has uncertain origins but a strong candidate for a cognate is the Baltic word zeme meaning "ground, earth, country." In another approach, Finnish suo means "fen," which is one of the characteristic biotypes of Finland; it is thought that Finland might have been called Suomaa by the early Finns. In Finnish, suomaa means Fen Land (Land of the Fens). The exonym Finland has resemblance with e.g. the Scandinavian placenames Finnmark, Finnveden and Finnskogen and all are thought to be derived from finn, a Germanic word for nomadic "hunter-gatherers" (as opposed to sedentary farmers). How, why and when this designation would have started to mean the Finns in particular is largely unknown. Among the first written documents mentioning a "land of the Finns" are two rune stones. There is one in Söderby, Sweden, with the inscription finlont and one in Gotland, a Swedish island in the Baltic Sea, with the inscription finlandi dating from the 11th century
(From Wikipedia)