An Etymological Dictionary of the German Language/Annotated/zwier

by Friedrich Kluge

zwier, adverb, ‘twice,’ earlier Modern High German, from the equivalent Middle High German zwir, Old High German zwirôr, zwiro; compare Old Icelandic tysvar, tvis-var (-var corresponding to Sanscrit vâra, ‘time’). Old High German drirôr, ‘thrice,’ is similarly formed.