From Longman Dictionary of Contemporary Englishgrand operaˌgrand ˈopera noun [countable, uncountable]  APMan opera with a serious subject in which all the words are sung
                                                    
                                                Examples from the Corpus
grand opera• Elizabeth is an extraordinary mixture of epic film, grand opera and grand guignol.• It is a setting worthy of grand opera.• A portion of the festival was devoted to grand opera. 
