Archimandrite, from the Greek for head of the sheepfold or head of the enclosure, was originally the title of a monk placed in charge of one or several monasteries within a diocese, exercising a coordinating authority over their abbots on the bishop's behalf; the term has broadened considerably in modern Orthodox practice, becoming primarily an honorific rank conferred by a bishop on a senior, unmarried, hieromonk in recognition of learning, administrative service or standing within the church, whether or not the recipient actually governs a monastery.
Because Orthodox bishops are drawn exclusively from the celibate, monastic clergy, the rank of archimandrite functions in practice as a visible marker of the pool from which future bishops are most often selected, though holding the title creates no automatic path to episcopal consecration. An archimandrite is entitled to wear certain pontifical-style vestments, including a form of mitre, during services, a visible distinction from an ordinary hieromonk that reflects the rank's standing as the senior grade among monastic priests below the episcopate itself.
Notable holders of the title have included administrators of major monastic complexes and heads of church diplomatic and educational institutions, since the rank has historically been conferred not only for monastic leadership but for scholarly and representative service to the wider church, a usage that broadened considerably during the nineteenth and twentieth centuries as Orthodox churches expanded their seminaries, publishing houses and foreign missions.