Rosalie is the French diminutive of Rose — from the Latin rosa. Saint Rosalia of Palermo (1130-1166) is the patron saint of Sicily, where her feast day on September 4 is a major celebration.
Rosalie entered the U.S. top 1000 in 1881 and has been continuously used since. It is rising now — the broader return of long classical names with flower roots (Rosalie, Rosalind, Marigold, Magnolia) has brought it back. Today it sits in the U.S. top 200.
Rosalie reduces to six — the number of soft beauty.