An Etymological Dictionary of the German Language/zwier

by Friedrich Kluge

zwier, adv., ‘twice,’ earlier ModHG., from the equiv. MidHG. zwir, OHG. zwirôr, zwiro; comp. OIc. tysvar, tvis-var (-var corresponding to Sans. vâra, ‘time’). OHG. drirôr, ‘thrice,’ is similarly formed.