I. A town in the interior of Campania, N. E. of Naples, now Acerra, exposed to frequent inundations from the Clanius, on which it is situated; hence in Verg.: vacuis Clanius non aequus Acerris, G. 2, 225 Wagner; imitated by Silius, 8, 538.—Deriv.,
II. A town in Umbria, called, for the sake of distinction, Acerrae Vatriae, now Gerrha, Plin. 3, 14, 19, § 114.