leisa, feasts and sacrifices anciently solemnized in honour of the goddess Isis.—The Isia were full of the most abominable impurities; and for that reason, those who were initiated into them were obliged to take an oath of secrecy. They held for nine days successively, but grew so scandalous, that the senate abolished them at Rome, under the consulate of Piso and Gabinius. They were re-established by Augustus, and the emperor Commodus himself assisted at them, appearing among the priests of that goddess with his head shaven, and carrying the Anubis.