Note 531 — Chapter XXIII · THE PAPACY AND THE TEMPORAL POWERS IN THE LATER MIDDLE AGES
Reading edition
Certain periods of the day, set apart by the laws of the Church, for the duties of prayer and devotion; also certain portions of the Breviary to be used at stated hours. The seven canonical hours are matins and lauds, the first, third, sixth, and ninth hours, vespers, and compline.