Archiereus
From the Catholic Encyclopedia
(Russian, arkhierei).
A Greek word for bishop, when considered as the culmination of the priesthood. It is very much used in the liturgical books of the Eastern Orthodox and Eastern Catholic Churches for those services which correspond to the pontifical services of the Roman Rite. This word must not be confounded with protoiereus (archpriest), the highest ecclesiastical rank to which a married priest may attain in the Greek Church.
ANDREW J. SHIPMAN