The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A faction at the Council of Chalcedon who supported the installation of Proterius of Alexandria as Patriarch of Alexandria. Bringing the Proterians into communion was one of the conditions that Proterius' sucessor, Peter Mongus, ascended to the Patriarchate under. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.