a person's greatest piece of work, as in an art.

anything done with masterly skill

a masterpiece of improvisation.

a consummate example of skill or excellence of any kind

The chef's cake was a masterpiece.

a piece made by a person aspiring to the rank of master in a guild or other craft organization as a proof of competence.

noun

chef d’oeuvre , classic , cream * , cream of the crop * , flower , gem * , jewel * , magnum opus , masterstroke , master work , model , monument , perfection , pice de rsistance , prize , showpiece , standard , tour de force * , treasure , chef-d\'oeuvre , masterwork , brainchild , chef-d\'uvre , chef d\'oeuvre , creation , jewel , objet d\'art , tour de force