noun
1. : a social class occupying a position between the upper class and the lower class: as
a. : a class achieving prominence in modern times during the transition from a medieval to a modern economy and constituting a grouping of people (as artisans, independent farmers, tradesmen, and lesser officials) between the hereditary nobility on the one hand and the laborers and peasants on the other
b. : a class occupying a position (as in England) between the aristocracy and the working class
c. : a fluid heterogeneous socioeconomic grouping (as in the United States) having a status intermediate between the upper and the lower classes and composed principally of business and professional people, bureaucrats, and some farmers and skilled workers sharing common social characteristics and values
2. middle classes plural : an aggregate of social groupings that includes the upper middle class and the lower middle class