Množina: middle classes

The social class between the lower and upper classes; SYN. bourgeoisie.
Those members of society who earn their living by nonmanual labor. Their income is usually higher than that of the working class in recognition of greater skills. The subdivisions upper middle class and lower middle class refer respectively to the more skilled professions (doctors, lawyers, and so on) and white-collar workers (lower management, shopkeepers, and so on).
Karl Marx used the term bourgeoisie to refer to the capitalist class who do not live by the sale of their labor.

Occupying a socioeconomic position intermediate between those of the lower classes and the wealthy. middle class

Množina: middle classes