Rosalie is a French and Latin name derived from Rosa — with the -alie suffix giving it a flowing, melodic quality that Rosa alone doesn't quite achieve. On a female dog or cat, it reads as deliberately vintage and feminine, one step more romantic than Rose and one step less grand than Rosaline.
The Twilight Connection
Rosalie Hale is a prominent character in Stephenie Meyer's Twilight series — one of the Cullen vampires, described as strikingly beautiful. The franchise's cultural saturation between 2005 and 2012 planted the name in a generation's awareness, and some owners choosing Rosalie for a female pet are drawing on that association, consciously or not. The human name Rosalie has been climbing in baby name rankings since roughly 2008.
Sound and Breed Fit
Rosalie's four syllables make it more of a formal registry name than a daily calling name — most owners shorten it to Rosie or Rose in practice. The full name works beautifully for elegant, long-coated female breeds: Cavalier King Charles Spaniels, Irish Setters, breeds with a romantic carriage that matches the name.
The Counter-Reading: Rosie Dominance
The diminutive Rosie is far more common as a standalone pet name than Rosalie is. Owners who love the full form should know their dog will likely be called Rosie by most people who encounter the name on paperwork or a tag. Embracing that is part of choosing Rosalie.