Lewis & Short

Vŏlāterrae, ārum, f., an ancient town in Etruria, now Volterra, Liv. 10, 12; Cic. Rosc. Am. 7, 20.
Hence, Vŏlāterrā-nus, a, um, adj., of or belonging to Volaterrœ, Volaterran: Vada, a seaport belonging to the territories of Volaterrœ, now Torre di Vado, Plin. 3, 5, 8, § 50; Cic. Quint. 6, 24.
Plur. subst.: Vŏlāterrāni, ōrum, m., the inhabitants of Volaterrœ, the Volaterrans, Plin. 3, 5, 8, § 52; Cic. Caecin. 7, 18; id. Att. 1, 19, 4; Liv. 28, 45 al.