[n] the social class between the lower and upper classes [adj] occupying a socioeconomic position intermediate between those of the lower classes and the wealthy
bourgeois, bourgeoisie, conservative, lower-middle-class, materialistic, upper-middle-class
low-class, lower-class, upper-class
bourgeoisie, burgherdom, common people, common run, common sort, commonage, commonality, commonalty, commoners, commons, fourth-rater, laborers, linendrapers, lower classes, lower middle class, lower orders, lumpen proletariat, mediocrity, Middle America,