1909 Catholic Dictionary
Commonly meant, in the Middle Ages, a ritual book containing directions for liturgical functions not including prayers; directions for a single function, or for several functions, e.g., the rite of Baptism, the consecration of a church, Extreme Unction, etc.; and a brief conspectus of daily office and Mass adapted to local calendars. A considerable number of Ordines are preserved among manuscripts from the 8th to the 12th century.