An Etymological Dictionary of the German Language/Annotated/Zitteroch
Zitteroch, masculine, ‘herpetic eruption,’ from the equivalent Middle High German ziteroch, Old High German zittaroh (hh), masculine (ttr remains unpermutated as in zittern); corresponding to Anglo-Saxon tëter, English tetter, to tetter. Allied in the non-Teutonic languages to Sanscrit dadru, dadruka, ‘cutaneous eruption,’ Lithuanian dedervine, ‘tether, scab,’ and Latin derbiosus (from derdviosus?). Anglo-Saxon tëter is based like Sanscrit dadru on an Aryan de-dru-, a reduplicated form (like Biber); Old High German zittaroh is borrowed from it.