Dictionary of Christian Biography and Literature to the End of the Sixth Century/Acephali
Acephali (from ἀ and κεφαλή, those without a head or leader) is a term applied:—(1) To the bishops of the oecumenical council of Ephesus in 431, who refused to follow either St. Cyril or John of Antioch—the leaders of the two parties in the Nestorian controversy. (2) To a radical branch of Monophysites, who rejected not only the oecumenical council of Chalcedon in 451, but also the Henoticon of the emperor Zeno, issued in 482 to the Christians of Egypt, to unite the orthodox and the Monophysites. Peter Mongus, the Monophysite patriarch of Alexandria, subscribed this compromise [ Acacius (7) ]; for this reason many of his party, especially among the monks, separated from him, and were called Acephali. They were condemned, under Justinian, by a synod of Constantinople, 536, as schismatics, who sinned against the churches, the pope, and the emperor. Cf. Mansi, Conc. tom. viii. p. 891 sqq.; Harduin, Conc. tom. ii, 1203 sqq.; Walch, Ketzerhistorie, vol. vii.; Hefele, Conciliengeschichte, vol. ii. pp. 549, 744. (3) To the clerici vagi, i.e. clergymen belonging to no diocese (as in Isid. Hispal. de Offic. Eccl., the so-called Egbert's Excerpts, 160, and repeatedly in Carlovingian Councils: see Du Cange) [D. C. A. art. Vagi Clerici ]. (4) It is said to be used sometimes for αὐτοκέφαλοι. [D. C. A. art. Autocephali.]