Magnum opus

Latin for a great work. Although a masterpiece is a work that demonstrates mastery, a magnum opus is the greatest work in the entire life of an artist, architect, filmmaker, or a writer. Many regard Mona Lisa (La Joconde) as Leonardo's magnum opus.Also see aesthetics, assessment, craftsmanship, goal, motivation, nuance, posterity, quality, standards, success, and virtuosity.