An ordinal, in a modern context, is a liturgical book that contains the rites and prayers for the ordination and consecration to the Holy Orders of deacons, priests, and bishops in multiple Christian denominations, especially the Edwardine Ordinals within Anglicanism. The term "ordinal" has been applied to the prayers and ceremonies for ordinations in the Catholic Church, where the pontificals of the Latin liturgical rites typically compile them along with other liturgies exclusive to bishops. In medieval liturgies, ordinals supplied instruction on how to use the various books necessary to celebrate a liturgy and added rubrical direction.

In certain Christian denominations, holy orders are the ordained ministries of bishop, priest (presbyter), and deacon, and the sacrament or rite by which candidates are ordained to those orders. Churches recognizing these orders include the Catholic Church, the Eastern Orthodox, Oriental Orthodox, Anglican, Assyrian, Old Catholic, Independent Catholic and some Lutheran churches. Except for Lutherans and some Anglicans, these churches regard ordination as a sacrament.