The terms "semi-opera", "dramatic[k] opera" and "English opera" were all applied to Restoration entertainments that combined spoken plays with masque-like episodes employing singing and dancing characters. They usually included machines in the manner of the restoration spectacular. The first examples were the Shakespeare adaptations produced by Thomas Betterton with music by Matthew Locke. After Locke's death, a second flowering produced the semi-operas of Henry Purcell, notably King Arthur and The Fairy-Queen. Semi-opera received a deathblow when the Lord Chamberlain separately licensed plays without music and the new Italian opera. Semi-operas were performed with singing, speaking and dancing roles. When music was written, it was usually for moments in the play immediately following either love scenes or those concerning the supernatural. It has been observed that several of Calderón's comedias with music by Juan Hidalgo de Polanco are closer to semi-opera than to the pastoral Zarzuela. Source: Wikipedia (en)