demi-monde
Concise Oxford English Dictionary © 2008 Oxford University Press:
demi-monde /ˌdɛmɪˈmɒnd/
▶noun a group considered to be on the fringes of respectable society.
– origin C19: Fr. (orig. with ref. to 19th-cent. France and the class of women considered morally dubious), lit. ‘half-world’.
'demi-monde' also found in these Oxford entries:

