Trasimeno (träzēmāˈnō) [key], Lat. Trasimenus, lake, c.50 sq mi (130 sq km), in Umbria, central Italy, W of Perugia. It is also called Lake of Perugia. The shallow circular lake (max. depth 19 ft/6 m) often floods its shores, which are sparsely populated. There is no natural outlet, but a subterranean channel to a tributary of the Tiber was opened in 1898. In 217 B.C., lake Trasimeno was the scene of Hannibal's victory over the Romans under Flaminius.