Sacrament
Latin sacramentum, "sacred oath"; translating Greek mystērion
Definition
An efficacious sign of grace, instituted by Christ and entrusted to the Church, by which divine life is given to us.
There are seven: Baptism, Confirmation, Eucharist, Penance, Anointing of the Sick, Holy Orders and Matrimony. They act ex opere operato — "by the very fact of the action being performed" — because Christ is at work in them, not because of the minister's personal holiness (CCC 1128).