What is "hipermestra"

Hipermestra is an opera in a prologue and 3 acts by Francesco Cavalli - more specifically, it is a festa teatrale. The opera was set to a libretto by G. A. Moniglia, and was first performed at Florence on 12 June 1658. The plot is based upon the ancient tale of Hypermnestra, a story that later served as a basis for a well-known libretto by Metastasio.