petit bourgeois
Concise Oxford English Dictionary © 2008 Oxford University Press:
petit bourgeois/petiˈbʊəʒwɑː/
▶adjective of or characteristic of the lower middle class, especially in being conventional and conservative. ▶noun (pl. petits bourgeois pronunc. same) a petit bourgeois person.
– origin Fr., lit. ‘little citizen’.
'petit bourgeois' also found in these Oxford entries:

