Arnus, i, m., = Ἄρνος, a river of Etruria, now the Arno, Plin. 3, 5, 8, § 50; Tac. A. 1, 79 al.; cf. Mann. Ital. I. 328.
Hence, Arnĭensis, e, adj., of or pertaining to the Arnus: tribus, situated on the Arnus, acc. to Liv. 6, 5, settled A. U. C. 396, most distant from Rome, as Saburana was the nearest: a Saburană usque ad Arniensem, Cic. Agr. 2, 29.