An Etymological Dictionary of the German Language/zwei
zwei, num., ‘two,’ from the equiv. MidHG. zwëne, m., zwô, f., zwei, n.; OHG. zwêne, m., zwo, f., zwei, n.; common to Teut. and Aryan. Comp. OSax. twêne, m., twô, twâ, f., twei, n.; Goth. twai, m., twôs, f., twa, n.; AS. twêgen, m., twô, f., tû, n.; E. two, Du. twê, OFris. twêne, m., twâ, f., twâ, n.; OIc. tveir, m., tvœr, f., tvau, n.; Swed. tvâ, Dan. to, tvende, m., to, f., to, n. Comp. further zwanzig and zwölf. Corresponding in the non-Teut. languages to Sans. dva, Zend dva, Gr. δύο, Lat. duo, OIr. dá, Lith. dù, Russ. dva. In earlier ModHG. the forms for the different genders were kept separate (zween, m., zwo, f., zwei, n.), until in the 17th cent. the neuter form became the prevalent one. For further cognates see Zweifel and Zwist. —