Rosary (Lat. rosarium), the name given by Roman Catholics to a certain form of prayers recited on a string of beads, and to the beads themselves. This form of prayer was instituted in the 13th century by St. Dominic, as a popular way of meditating on the chief mysteries of Christ's life. It consists of 15 times 10 small beads, every 10 small ones being preceded by one larger one. At each large bead the Lord's prayer is recited, and at each of the smaller ones the "Hail Mary," the 10th "Hail Mary" being followed by the doxol-ogy: "Glory be to the Father, and to the Son, and to the Holy Ghost," etc. In each "Hail Mary," after the word "Jesus," which concludes the first half of it, a few words commemorative of a mystery in the life of Christ are inserted. The rosary was intended to be for the laity what the breviary is for the priests; and as the number of "Hail Marys" in the rosary is equal to the number of psalms in the breviary, it is often called psalterium Marianum. The name rosarium (in mediaeval Latin) is probably derived from the appellation rosa mystica, by which the Virgin Mary is frequently designated in the prayers of the church.

On account of the length of the original rosary, it soon became and still is customary to take for common use only one third of it, which is also called "the small rosary," and popularly the crown (corona) or chaplet of the Blessed Virgin. - The Buddhists and Mohammedans likewise use beads for counting their prayers, those of the latter being commonly formed of sacred clay of Mecca or Medina. (See Bead).