Lewis & Short

bĭjŭgus, a, um (contr. form bīgus, Manil. 5, 3; cf. also bĭjŭgis, e), adj. [bis-jugum],

  1. I. yoked two together (poet.): leones, Lucr. 2, 602; Verg. A. 10, 253: equi, Mart. 1, 13, 8: serpentes, Val. Fl. 7, 218: currus, drawn by two horses, Lucr. 5, 1299: temo, Stat. Th. 2, 723: certamen = bigarum, the contest with the bigae, Verg. A. 5, 144.
  2. II. Subst.: bĭ-jŭgi, ōrum, m. (sc. equi), two horses yoked abreast: telo Admonuit bijugos, Verg. A. 10, 587; 10, 399: desiluit Turnus bijugis, i. e. from his chariot drawn by two horses, id. ib. 10, 453.