ACEPHALI (6,140aXot), a term applied to sects having no head or leader; and in particular to a strict Monophysite sect that separated itself, in the end of the sth century, from the rule of the patriarch of Alexandria (Peter Mongus), and remained "without king or bishop" till it was reconciled by Mark I. (799-819) (Gr. a, privative, and KaPaXi, head).