diaconus

Diaconus is the Latin title for a deacon, a member of the Christian clergy who ranks below priest and bishop. The word derives from the Greek diakonos, meaning servant, minister, or helper, and entered Latin usage as Christianity spread in the Roman world. In early Christian communities, the diaconate developed as a distinct order; deacons served the poor, assisted bishops and priests at liturgical celebrations, and performed charitable and administrative tasks such as the distribution of alms.

In the Latin Church and its descendants, the diaconate comprises either transitional deacons, who are ordained as part of preparation for priesthood, or permanent deacons, who remain in the office for life. The diaconal role includes liturgical duties—proclaiming the Gospel, preaching the homily, assisting at the Eucharist, and distributing Holy Communion—and, in many rites, baptizing, witnessing marriages, and presiding over funerals. Deacons do not normally preside over the consecration of the Eucharist or absolve sins, functions reserved to priests and bishops, though practices vary by rite.

Across other traditions—Eastern Orthodox, Oriental Orthodox, and some Eastern Catholic Churches—the term is similarly rendered as deacon, with analogous duties in liturgical service and charity. In scholarly literature, diaconus is encountered in Latin patristic and liturgical texts to designate the office, its origin, and its development within ecclesiastical hierarchy. Related terms include deacon, diaconate, and diaconate ordination.