Why is it "masterpiece" and not "a piece of art"?
Why do you say masterpiece, and not piece of art?
Solution 1:
Well, people do say “a piece of art”, but “masterpiece” is usually a very special piece (or work) of art. Quoting Wikipedia,
Masterpiece (or chef d'œuvre) in modern usage refers to a creation that has been given much critical praise, especially one that is considered the greatest work of a person's career or to a work of outstanding creativity, skill or workmanship.