[ ˌmagnəm'əʊpəs , 'ɒpəs ]
■ noun ( plural ~es or magna opera ˌmagnə 'əʊpərə , 'ɒpərə ) a work of art, music, or literature that is regarded as the most important or best work that an artist, composer, or writer has produced.
Origin
C18: from L., 'great work'.