magnum opus

From Latin magnum opus (“great work”).[1]

• (Latin) IPA^(key): /ˌmaŋnũː ˈopus/
• (Received Pronunciation) enPR: măg'nəm ōʹpəs, IPA^(key): /ˌmæɡnəm ˈəʊpəs/
• (US) enPR: măg'nəm ōʹpəs, IPA^(key): /ˌmæɡnəm ˈoʊpəs/

magnum opus (plural magna opera or magnum opuses or magnum opi)

1. A great or important work of literature, music or art, a masterpiece.
2. The best, most popular, or most renowned achievement of an author or artist, representing their major life effort.

   The 1949 novel Nineteen Eighty-Four is widely considered to be George Orwell's magnum opus.

The Latin plural magna opera may be preferred in some academic and literary contexts, in popular usage the English-style plural magnum opuses is more common. The plural magnum opi, although rare and likely regarded as incorrect in formal works, does see some use.

• masterpiece
• opus magnum
• seminal work

• magnum opus on Wikipedia.Wikipedia

• opus magnum