Demi-monde refers to a group of people who live hedonistic lifestyles, usually in a flagrant and conspicuous manner. The term was commonly used in Europe from the late 18th to the early 20th century, and modern use often refers to that period. Its connotations of pleasure-seeking often contrasted with wealth and ruling class behavior.
The term was often used as one of disapprobation, the behavior of a person in the demimonde being contrary to more traditional or bourgeois values. Such behaviors often included drinking or drug use, gambling, high spending (particularly in pursuit of fashion, as through clothing as well as servants and houses), and sexual promiscuity. The term demimondaine referred to a woman who embodied these qualities; later it became a euphemism for a courtesan or prostitute.
The term ‘demi-monde’ is French for “half-world”. It derives from a comedy by Alexandre Dumas fils published in 1855 called Le Demi-Monde.