Lewis & Short

ferrātus, a, um, adj. [ferrum], furnished, covered, or shod with iron.

  1. I. Adj.: postes, Enn. ap. Serv. Verg. A. 7, 622 (Ann. v. 271 ed. Vahl.); imitated, Verg. A. 7, 622: orbes rotarum, Lucr. 6, 551; Verg. G. 3, 361: hasta, Liv. 1, 32, 12: sudes, Verg. A. 5, 208: capistra, id. G. 3, 399: calx, armed with a spur, id. A. 11, 714: servi, i. e. fettered (sc. catenis), Plaut. Bacch. 4, 6, 11; cf. the preced. art.: agmina, i. e. iron-clad, in armor, Hor. C. 4, 14, 30: aquae, ferruginous, chalybeate, Sen. Q. N. 3, 2: forma suum, iron, made of iron, Val. Fl. 6, 90.
  2. II. Subst.: ferrāti, ōrum, m. (sc. milites): in fronte statuerat ferratos, in cornibus cohortes, harnessed soldiers, cuirassiers, Tac. A. 3, 45.