middle class 
noun [treated as singular or plural]
The social group between the upper and working classes, including professional and business people and their families: the urbanization and expansion of the middle class commerce brought ever-increasing wealth to the middle classes...
- I want the working class and the middle class and the upper class, and in Britain I've got it.
- The working classes and middle classes are now at the mercies of the regional land market.
- A great many collectors from the upper aristocracy or rich middle classes called on her skill.
adjective
1Relating to the middle class: a middle-class suburb...
- A middle-class boy from the suburbs would have picked up a camera at art school, but Jobson took two decades to find his metier.
- Some comprehensives, particularly those in middle-class suburbs, succeed.
- And he found a sedate, respectable, middle-class partner from the suburbs of London.
1.1Characteristic of the middle class, especially in attaching importance to convention, security, and material comfort: a rebellion against middle-class values...
- It endorses mainstream and largely middle-class values and language.
- Kate was middle-class and comfortable, and her father was a magazine editor.
- It is less clear that Scotland is comfortable with becoming more middle-class.
Derivatives
middle-classness
- The emphasis on the supposed correctness of their English denotes a certain amount of middle-classness.
- There's been a lot written of late about the middle-classness of rock groups such as Keane, as if this was a relatively recent aspect of pop culture, proof at last of an equitable society.