An Etymological Dictionary of the German Language/rünstig

by Friedrich Kluge

rünstig, adj., ‘flowing, running,’ in blutrünstig, ‘bleeding, bloody,’ from MidHG. bluot-runsec, -runs, adj., ‘bloody, wounded,’ allied to MidHG. and OHG. bluot-runs, ‘hæmorrhage, bleeding wound.’ Runs is an abstract from rinnen; comp. Goth. runs (gen. runsis), ‘course,’ runs blôþis, ‘issue of blood.’ Hence also ModHG. (dial.) Runs, ‘course of a torrent.’