(Ἀέριος), Heretic, the intimate friend of Eustathius of Sebaste in Armenia, A. D. 360, was living when St. Epiphanius wrote his Book against Heresies, A. D. 374-6. After living together an ascetic life, Eustathius was raised to the episcopate, and by him Aerius was ordained priest and set over the Hospital (πτωχοτροφεῖον) of Pontus. (St. Epiph. ad v. Haer. 75.1.) But nothing could allay the envy of Aerius at the elevation of his companion. Caresses and threats were in vain, and at last he left Eustathius, and publicly accused him of covetousness. He assembled a troop of men and women, who with him professed the renunciation of all worldly goods (ἀποταξία). Denied entrance into the towns, they roamed about the fields, and lodged in the open air or in caves, exposed to the inclemency of the seasons. Aerius superadded to the irreligion of Arius the following errors : 1. The denial of a difference of order between a bishop and a priest. 2. The rejection of prayer and alms for the dead. 3. The refusal to observe Easter and stated fasts. on the ground of such observances being Jewish. St. Epiphanius refutes these errors. (l.c. There were remains of his followers in the time of St. Auguistine. (Adv. Haer. § 53, vol. viii. p. 18, which was written A. D. 428.)