the ancient Frusino, a town of the Papal States, capital of a cognominal delegation, at the foot of a hill near the left bank of the Cosa, 46 miles E.S.E. of Rome. The ancient city stood on the Via Latina. It originally belonged to the Volsci, and was subsequently colonized by Roman veterans. Some remains of an amphitheatre are still visible in the plain beneath, but the town itself contains no relics of antiquity. The town is very ill built, but has numerous churches and convents. It is the seat of a bishopric, and of a court of primary jurisdiction. A large annual fair is held here. Being situated near the Neapolitan territory, its neighbourhood is notorious for brigandage. Pop. about 7000.

The delegation of Frosinone is bounded on the N. and N.W. by the Comarca di Roma, S. and S.W. by the Mediterranean, and on the E. and S.E. by the Neapolitan province of Terra di Lavoro. It has an area of 720 square miles, and a population (1850) of 148,378.