Reduced from Lapvesi (through generalization of the genitive form Lapve(d)en), originally a term for the southern parts of the lake Saimaa. This is probably reduced from even earlier Lappavesi, where the latter component is vesi(“water”) and the former may be related to lappalainen.[1]
^ Sirkka Paikkala, editor (2007), Suomalainen paikannimikirja [Book of Finnish Place names] (in Finnish), Helsinki: Karttakeskus, Kotimaisten kielten tutkimuskeskus, →ISBN