SECONDIANO, bishop of SINGIDUNO. — In 366 he was still a priest and a follower of Ursacius and Valens, as appears from the letter they addressed to Germinius, bishop of Sirmium (CSEL, 65, p. 180).
Having become a bishop, he was judged and condemned as a Homoian in 378 at Sirmium, but he appealed to the emperor Gratian, asking to be judged and heard in a general council, which could be convened only in 381 at Aquileia, under the direction of St. Ambrose. Despite his evasions, S. was exposed as a heretic and condemned.
BIBL.: Tillemont, X, p. 126 ff.; Hefele-Leclercq, II, pp. 49–51; Mansi, III, pp. 600–32; Fliche-Martin-Frutz, III, p. 288 f. Agostino Amore