Verismo, a term originally applied to nineteenth-century art and literature of various degrees of realism, has been the subject of controversy when applied to opera. While literary scholarship has come to measure verismo against the narrowly defined models provided by the theories, novels, and short stories of Luigi Capuana and Giovanni Verga, operatic scholarship has either superimposed these same theories on the dramatic genre of the libretto or it has constructed concepts of questionable historical foundation. Drawing mainly on a large corpus of neglected nineteenth- and early twentieth-century discussions of verismo, this article uncovers the original meanings of the termand outlines how we have come to adopt a view of verismo that is problematic in regard to both literature and opera. Contrary to this view, verismo was seen in the nineteenth century primarily as a reaction to the idealism and conventionality of earlier artworks; in this sense it had already been applied to opera before 1890, and it is, in fact, a perfectly appropriate designation for opera in the late nineteenth and early twentieth centuries. In comparison to Romantic Italian opera, with its conventional forms of both libretto and music, verismo opera reacts to idealism in any combination of categories ranging from plot to vocabulary, verse, harmony and melody, performance practice, and production.