I. A river in Thrace, now the Mesto or (Turkish) Karasu, Liv. 45, 29, 6; also called Nestos ( = Νέστος), Mel. 2, 2.—
II. A Centaur, who, on offering violence to Dejanira, was slain by Hercules with a poisoned arrow, Ov. M. 9, 101 sq.; Hyg. Fab. 34.—Hence,
III. Nessēus , a, um, adj., of Nessus: “venenum,” with the blood of Nessus, poisoned by the arrow of Hercules, Ov. H. 9, 163: “palla tabe Nesseā illita,” Sen. Herc. Oet. 716.