archdeacon n.

also archi-, word-forming element meaning "chief, principal; extreme, ultra; early, primitive," from Latinized form of Greek arkh-, arkhi- "first, chief, primeval," combining form of arkhos "a chief, leader, commander," arkhein "be first, begin" (see archon).

Middle English deken, "one who reads the Gospel in divine worship, one of a body of assistants to a priest or other clergyman," from Old English deacon, diacon, from Late Latin diaconus, from Greek diakonos "servant of the church, religious official," literally "servant," from dia- here perhaps "thoroughly, from all sides," + PIE *kon-o-, from root *ken- "to hasten, set oneself in motion." Related: Deaconess; deaconship.