While editing and rewriting sections of my novel about medieval France I have been researching the development of the rosary. I came across a fascinating blog called Paternosters which was a name given to prayer beads in the medieval period. Here is an article about the origins of the the word "rosary" which I found quite interesting. To quote:
To get back to beads, however, traces of the earlier meaning of bid/bede as "a prayer" still remain. For instance, a wealthy patron in the Middle Ages may have supported poor bedesmen, who had promised to pray for the patron, and may have provided a bedehouse for bedesmen or bedeswomen to live in. Likewise, “bidding one’s bedes” in the Middle Ages does not so much mean praying with a literal string of beads, as it means praying for one’s bedes, that is, the people or requests one is obliged to pray for.
The word “rosary” originally meant a garden devoted to the growing of roses (c1440, “This mone is eke rosaries to make, with setes [seats]”)....Probably both the rose-garden concept and the book title contributed to the idea of referring to a collection of written prayers and devotions as a (metaphorical) rosary, such as the 1526 Rosary of Our Savyour Jesu or the 1533 Mystik sweet Rosary of the faytheful soule.
From here it was a short step to applying the term “rosary” to the specific prayer practice we have been discussing, including its string of beads.
Other European languages also call the rosary by a name referring to roses. In German it is a rosenkranz, in French a rosaire, in Italian and Spanish a rosario, and in Hungarian it is a rózsafüzért (literally a “rose string”). However in Austria it is more commonly a betschnur (“prayer string”) and in France, often a chapelet.