The Spanish word 'opus' comes directly from the Latin word 'opus', meaning 'work'. In Spanish, the meaning has become specialized to refer specifically to a musical work, particularly in the context of numbering musical compositions. This term is commonly used in classical music to identify and catalog a composer's works chronologically.

While 'opus' is a relatively specialized term in Spanish, it's worth noting that the more common Spanish word 'obra' (meaning 'work' or 'piece') is used in similar contexts, though 'opus' is specifically reserved for classical music cataloging.

The English language also borrowed 'opus' directly from Latin, using it in the same way as Spanish to refer to a musical composition or work. You might recognize it in phrases like 'magnum opus' (meaning 'great work' or masterpiece). The word 'operate' and its derivatives (operation, operative, etc.) also come from the same Latin root, as they all relate to the concept of work or activity.