An Etymological Dictionary of the German Language/zwanzig

by Friedrich Kluge

zwanzig, num., ‘twenty,’ from the equiv. MidHG. zweinzec, zwênzic, OHG. zweinzug; a common West Teut. numeral. Comp. OSax. twêntig, LG. and Du. twintig, OFris. twintich, AS. twêntig (from twœ̂gentig?), E. twenty (see -zig). The n of the first component seems to be a mark of the nom. plur. masc., as in OHG. zwên-e, AS. twêgen; see zwei.