Lewis & Short

Lūsĭtānĭa, ae, f., the western part of Spain, the mod. Portugal and a part of the Spanish provinces of Estremadura and Toledo, Caes. B. C. 1, 38, 2; Liv. 21, 43, 8; 27, 20; Mel. 2, 6, 3 sq.; 3, 1, 6; 3, 6, 2; Liv. Ep. 52; Plin. 4, 21, 35, § 113.
Hence, Lū-sĭtānus, a, um, adj., of or belonging to Lusitania, Lusitanian: cerasa, Plin. 15, 25, 30, § 103: tela, Val. Max. 9, 1, n. 5.
In plur. subst.: Lūsĭtāni, ōrum, m., the Lusitanians, Cic. Brut. 23, 89; Liv. 35, 1; 37, 46 sq.; Plin. 4, 22, 35, § 116.