An Etymological Dictionary of the German Language/Annotated/Harn
Harn, masculine, ‘urine,’ earlier dialectic variant Harm (Luther), from Middle High German harn (Bavarian and East Rhenish), harm, masculine and neuter, Old High German haran, masculine, ‘urine’ (respecting the variant with m see Farn); a specifically Upper German word, probably identical originally with Anglo-Saxon scearn, Old Icelandic skarn, neuter, ‘mud’; sk and h (the latter for k without s) would have interchanged in Old Teutonic. Allied to Greek σκώρ; compare hocken, drosseln, links, Stier. The derivation of Harn from a root har, ‘to pour out,’ remains dubious.