The name Rosmerta is a girl's name . Rosmerta and is often added to lists like Names from Harry Potter.
From the experts:
Rosmerta is a Gallo-Roman goddess of fertility, abundance, and prosperity, often depicted holding a cornucopia. In the Harry Potter books, Madame Rosmerta is the landlady of the Three Broomsticks pub in the wizarding village of Hogsmeade.