Lewis & Short

bīgātus, a, um, adj. [bigae], having the figure of a bigae (exclusively of coin); with the figure of a bigae stamped upon it (cf. Dict. of Antiq.): argentum, Liv. 33, 23, 7; 33, 37, 11; 36, 21, 11.
Also, subst.: bīgā-tus, i, m. (sc. nummus), a silver coin with the stamp of the bigae, Plin. 33, 3, 13, § 46: nummi quadrigati et bigati a figurā caelaturae dicti, Paul. ex Fest. s. v. grave aes, p. 98 Müll.; Liv. 23, 15, 15; Tac. G. 5.