the open world, in Roman antiquity, a solemnity performed in a small temple, of a round form like the world, dedicated to Dir and the rest of the infernal gods. This temple was opened but three times in the year, viz. the 24th of August, the 4th of October, and the 7th of November. During these days, the Romans believed hell was open; on these days therefore they never offered battle, lifted soldiers, put to sea, or married.