Word of the Day:

: a great work; especially : the greatest achievement of an artist or writer

Moby-Dick is widely regarded as Herman Melville's magnum opus.

"The 'visual album' came to us intimately, a surprise delivered in the night without PR apparatuses or label hype machines, with a magical, delectable set of videos to match. That it's already been hailed by almost every critical body as a magnum opus is no wonder, considering both the delightful unexpectedness of its delivery and its stunning, detailed lushness." - From a review by Devon Maloney in The Village Voice, January 15, 2014

More example sentences

You probably recognize "magnum" ("great") as a Latin word that shows up in altered forms in several English words, and perhaps you can also come up with a few that are related to "opus" ("work"). "Magnitude," "magnanimous," "opulent," and "operate" are some obvious relations of the two. "Magnum opus," which entered English in the late 18th century, retains the original Latin spelling and the literal meaning "great work." Although the term most often refers to literary productions, it has been used to describe many kinds of great works, including paintings, movies, construction projects, and even surgical techniques.