Literaturoper (literature opera, plural “Literaturopern”), a term coined by the German music critic Edgar Istel, describes a genre of opera that emerged during the late 19th century. When an existing play for the legitimate theatre is set to music without major changes and without the intervention of a librettist, a “Literaturoper” is the result. Although the term is German, it can be applied to any kind of opera, irrespective of style or language. (In that sense it can be regarded as a term rather than a genre as such.)