Lewis & Short

dŭŏ, ae, ŏ (acc. masc. duo as freq. as duos; cf. ambo. Passages with duo, Att. ap. Charis. p. 101 P.; Plaut. Ep. 2, 2, 4; 3, 2, 37; id. Most. 3, 2, 89; 147; 148; id. Ps. 1, 3, 99; 4, 2, 43; Varr. R. R. 1, 18, 5; 3, 1, 9; Cic. Rep. 1, 10; 1, 13; 2, 14; 2, 19; id. Verr. 2, 2, 9; id. Tull. § 19 Beier N. cr.; id. Fam. 3, 4, 2; 7, 25, 2; id. Att. 9, 11, A, 2; Caes. B. G. 7, 69, 2; Liv. 6, 42 fin.; 35, 21; Suet. Calig. 41; id. Oth. 1, 5; Verg. A. 11, 285; Hor. S. 1, 7, 15 al.
Gen. duūm, Naev. ap. Charis. p. 102 P.; Att. ap. Cic. Or. 46 fin.; Lentul. ap. Cic. Fam. 12, 15, 2; Sall. J. 106, 5; Liv. 3, 25; Plin. 12, 19, 42, § 89; 15, 17, 18, § 63 et saep.
Neutr. dua, Att. ap. Cic. Or. 46 fin.; and connected with pondo, also duapondo, Vitr. 10, 17; Scrib. Comp. 45; cf. Quint. 1, 5, 15.
The metre dŭō occurs only in Aus. Ep. 19, 13), card. num. [Sanscr. dva; Gr. δύο, δύω; Goth. tvai; Germ. zwei; Engl. two; cf.: bis (for dvis), dubius, duplex, etc.].

  1. I. Two: hi ambo et servus et hera frustra sunt duo, Plaut. Am. 3, 3, 19: angues duo maxumi, id. ib. 5, 1, 56: duo talenta argenti, id. As. 1, 3, 41 et saep.
  2. II. = Gr. οἱ δύο, the two, both: subito edicunt duo consules, Cic. Sest. 14, 32: duo sapientia praestantes, pater et socer, Nep. Tim. 3, 2: nocuit sua culpa duobus, Ov. M. 15, 115; cf.: vos inter duos, Plaut. Am. 3, 2, 2: qui duo populi, Liv. 8, 17, 9.