“ opus ”
o‧pus /ˈəʊpəs $ ˈoʊ-/ noun (plural opuses oropera /ˈɒpərə $ ˈɑː-/) [usually singular]
1. a piece of music by a great musician, numbered according to when it was written
2. formal an important work of art by a famouswriter, painter etc
––– longman translator