1
masterpiece;masterwork;chef d'oeuvre;fine piece of work
その偉大な画家の傑作が壁にさかさまにかかっているを見て、彼は驚いた。
He was surprised to find the great artist's masterpiece hung on the wall upside down.
2
(unintentionally) hilarious;absurd (e.g. blunder);outrageous;wild
わははは!そりゃ傑作だ!
A-ha-ha-ha! What a blunder!