Roslagen

Probably from Old Swedish Roþslaghen, from Roþs, genitive form of Roþer (“Roden”) + laghen, definite plural form of lagh (“corporation, community”).^[1]

Roslagen n (genitive Roslagens)

1. Roslagen (the coastal areas of Uppland)

   Synonym: (historical) Roden

   • 1932, Evert Taube, “Calle Schewens vals [Calle Schewen's Waltz]”‎^[2]:

     I Roslagens famn på den blommande ö, där vågorna klucka [old present tense plural, usually kluckar] mot strand, och vassarna vagga [old present tense plural, usually vaggar] och nyslaget hö, det doftar emot mig ibland.

     In Roslagen's embrace on the flowering island, where the waves lap ["cluck" – onomatopoeic] against shore [sic – indefinite], and the reeds sway and of freshly mown hay, it wafts [smells pleasantly, "scents"] towards me sometimes [sic].

• rospigg (“person from Roslagen”)

• Roslagen in Svenska Akademiens ordlista (SAOL)