hi leenia,

"Reutter" is a historical form of the word "Ritter" (= knight) or "Reiter" (= rider).

It simply means "folksong". According to Lutz Röhrichs book " Gesammelte Schriften zur Volkslied- und Balladenforschung" the word "folksong" = Volkslied was first used by the poet, philosopher etc. Johann Gottfried Herder (born1744, died 1803); before that various words have been used from "cantus vulgi" to "Gassenhawerlin" or "Strassenlied" (last 2 can be translated as "street ballads").

Best wishes
Ernest