ADERNO, a city at the foot of Mount Aetna in Sicily, in the intendancy of Catania. It is built in an unhealthy situation, but contains 8000 inhabitants. It has several churches, the chief of which is supported by beautiful pillars of polished lava. It is the site of the ancient city Hadranum, whose ruins are still visible. On the river Giarretta, which passes the city, is a remarkable waterfall.