Mid 19th century; earliest use found in Elizabeth Gaskell (1810–1865), novelist and short-story writer. From French morceau de salon, lit. ‘salon piece’ from morceau + de + salon.
Definition of morceau de salon in US English:
morceau de salon
noun
Music
A well-known tune elaborated by variations, etc.
Origin
Mid 19th century; earliest use found in Elizabeth Gaskell (1810–1865), novelist and short-story writer. From French morceau de salon, lit. ‘salon piece’ from morceau + de + salon.