E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Rosary [the rose article].
A name given to the bead-roll employed by Roman Catholics for keeping count of their repetitions of certain prayers. It consists of three parts, each of which contains five mysteries connected with Christ or His virgin mother. The entire roll consists of 150 Ave Marias, 15 Pater Nosters, and 15 doxologies. The word is said by some to be derived from the chaplet of beads, perfumed with roses, given by the Virgin to St. Dominic. (This cannot be correct, as it was in use A.D. 1100.) Others say the first chaplet of the kind was made of rosewood; others, again, maintain that it takes its name from the Mystical Rose, one of the titles of the Virgin. The set is sometimes called fifteens, from its containing 15 doxologies, 15 Our Fathers, and 10 times 15 or 150 Hail Marys. (Latin, rosrium.)
The Devotion of the Rosary takes different forms:(1) the Greater Rosary, or recitation of the whole fifteen mysteries; (2) the Lesser Rosary, or recitation of one of the mysteries; and (3) the Living Rosary, or the recitation of the fifteen mysteries by fifteen different persons in combination.
In regard to the rosewood, this etymology is extremely doubtful. The beads are now made of berries, wood, stone, ivory, metal, etc., sometimes of considerable value.