An Etymological Dictionary of the German Language/-zig

by Friedrich Kluge

-zig, suffix for forming the tens, from MidHG. -zic (g), OHG. -zug; comp. zwanzig. In dreißig, from MidHG. drî-ȥec, OHG. drî-ȥug, there appears a different permutation of the t of Goth. tigus, ‘ten’; comp. AS. -tig, E. -ty. Goth. tigu- (from pre-Teut. dekú-) is a variant of taíhan, ‘ten.’ See zehn.