323. Why is this sacrament called Holy Orders?

323. Why is this sacrament called Holy Orders? 

(Comp 323) Orders designates an ecclesial body into which one enters by means of a special consecration (ordination). Through a special gift of the Holy Spirit, this sacrament enables the ordained to exercise a sacred power in the name and with the authority of Christ for the service of the People of God.

“In brief”

(CCC 1534) Two other sacraments, Holy Orders and Matrimony, are directed towards the salvation of others; if they contribute as well to personal salvation, it is through service to others that they do so. They confer a particular mission in the Church and serve to build up the People of God.

To deepen and explain

(CCC 1537) The word order in Roman antiquity designated an established civil body, especially a governing body. Ordinatio means incorporation into an ordo. In the Church there are established bodies which Tradition, not without a basis in Sacred Scripture (Cf. Heb 5:6; 7:11; Ps 110:4), has since ancient times called taxeis (Greek) or ordines. And so the liturgy speaks of the ordo episcoporum, the ordo presbyterorum, the ordo diaconorum. Other groups also receive this name of ordo: catechumens, virgins, spouses, widows,... 

Reflection

(CCC 1538) Integration into one of these bodies in the Church was accomplished by a rite called ordinatio, a religious and liturgical act which was a consecration, a blessing or a sacrament. Today the word "ordination" is reserved for the sacramental act which integrates a man into the order of bishops, presbyters, or deacons, and goes beyond a simple election, designation, delegation, or institution by the community, for it confers a gift of the Holy Spirit that permits the exercise of a "sacred power" (sacra potestas) (Cf. LG 10) which can come only from Christ himself through his Church. Ordination is also called consecratio, for it is a setting apart and an investiture by Christ himself for his Church. The laying on of hands by the bishop, with the consecratory prayer, constitutes the visible sign of this ordination.   

(Next question: What place does the sacrament of Holy Orders have in the divine plan of salvation?)