sostenuto Syllabification: (sos·te·nu·to)Pronunciation: /ˌsästəˈno͞otō/ MusicDefinition of sostenuto adjective (of a passage of music) to be played in a sustained or prolonged manner. noun (plural sostenutos) a passage to be played in a sustained and prolonged manner. the performance of a passage in a sustained or prolonged manner. Origin:Italian, 'sustained'sostenuto in other Oxford dictionaries Definition of sostenuto in the British & World English dictionary