Lewis & Short

Trăsŭmēnus (also Trăsymēnus, after Τρασυμένη λίμνη, in Strabo; and less correctly Trăsĭmēnus), Trasimenus lacus, or simply Trasimenus, Τρασιμένη λίμνη, a lake in Etruria, near Perusia, celebrated for Hannibal’s victory over the Romans, now Lago Trasimeno or Lago di Perugia, Cic. Div. 2, 8, 21; id. N. D. 2, 3, 8; id. Rosc. Am. 32, 89; id. Brut. 14, 57; Liv. 22, 4 sq.; Flor. 2, 6, 13; Val. Max. 1, 6, 6; Sil. 4, 739; 5, 8; Stat. S. 1, 4, 86; Plin. 2, 84, 86, § 200; 2, 107, 111, § 241; 7, 28, 29, § 106.
As adj.: Trasimena litora, Ov. F. 6, 765.
Hence, Trăsĭmēnĭcus, a, um, adj., of or belonging to Trasimenus, Trasimenian: strages, Sid. Carm. 9, 247.