While "magnum" is Latin for "great," it's not the root word. It's an adjective modifying "opus," which is the actual Latin word for "work."
Therefore, opus is the root word for "magnum opus," meaning a great work.
While "magnum" is Latin for "great," it's not the root word. It's an adjective modifying "opus," which is the actual Latin word for "work."
Therefore, opus is the root word for "magnum opus," meaning a great work.