Unknown. The original nominative was Saimas as part of Saimas wesi, Saimas selkä (1646). Possibly connected with the Sami endonym *sāmē.[1] Alternatively from an unknown substrate language.
^ Sirkka Paikkala, editor (2007), Suomalainen paikannimikirja [Book of Finnish Place names] (in Finnish), Helsinki: Karttakeskus, Kotimaisten kielten tutkimuskeskus, →ISBN