sostenuto
adverb, adjective/ˌsɒstəˈnjuːtəʊ/
/ˌsɑːstəˈnuːtəʊ/
(music, from Italian)- (used as an instruction) making each note last for its full written lengthWord OriginItalian, ‘sustained’.
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sostenuto
Definition of sostenuto adverb from the Oxford Advanced Learner's Dictionary