In the USA, UMC roughly means annual income of $1**000, with enough wealth to own a large house and other comforts, but not enough to own a congressperson.
Some words that don't seem right:
- bourgeoisie
- proletariat, common people - not financially secure.
- wealthy, elite, a-list - upper class.
- gentry, aristocracy - upper class and British.
- establishment - own congresspeople.
Example usage: "No, the {upper middle class} is not 'the establishment'."
A phrase is acceptable if it has fewer characters and syllables than "upper middle class".