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principal river in western Germany, from German Rhein, from Middle High German Rin, ultimately from Gaulish Renos, literally "that which flows," from PIE root *reie- "to move, flow, run" (cf. Sanskrit rinati "causes to flow," ritih "stream, course;" Latin rivus "stream;" Old Church Slavonic reka "river;" Middle Irish rian "river, way;" Gothic rinnan "run, flow," rinno "brook;" Middle Low German ride "brook;" Old English riþ "stream;" Old English rinnan, Old Norse rinna "to run," Dutch ril "running stream"). The spelling with -h- (cf. Latin Rhenus; French Rhin) is from influence of the Greek form of the name, Rhenos.
River in Europe, rising in the Alps of Switzerland and flowing generally north, passing through or bordering on Switzerland, Liechtenstein, Austria, Germany, France, and The Netherlands before emptying into the North Sea.
Note: A principal river of Europe, the Rhine carries more traffic than any other waterway in the world.