BALLAD OPERA, a simple type of opera peculiar to Eng land, where it had its origin in the 18th century, the story being usually in the nature of a burlesque or extravaganza, while the music, confined mainly to detached numbers interspersed among the spoken dialogue, was drawn from pre-existing popular ballads to which the words of the lyrics were adapted. The most famous of all such works was Gay's "Beggar's Opera," but many others enjoyed hardly less popularity. Save for occasional re vivals, the type is now extinct. (See MUSICAL COMEDY.)