A surname of Janus. It is said that after the conquest of the Faliscans an image of Janus was found with four foreheads. Hence afterwards a temple of Janus quadrifrons was built in the Forum transitorium, which had four gates. The fact of the god being represented with four heads is considered by the ancients to be an indication of his being the divinity presiding over the year with its four seasons. (Serv. ad Aen. vii. 607; Isid. Orig. viii. 11; August. De Civ. Dei. vii. 4.)