Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
Bēnācus, i, m., = Βήϝακος, Strabo: lacus, a deep and rough lake in Gallia Transpadana, near Verona, through which the Mincius (Mincio) flows, now Lago di Garda, Plin. 2, 103, 106, § 224; 9, 22, 38, § 75; and absol. Benacus, Verg. G. 2, 160; id. A. 10, 205.
Hence, Bēnācenses, ium, m., the people dwelling near Lake Benacus, Inscr. Grut. 260, 2.