APA Dictionary of Psychology

a major group or division of society having a common level of power and prestige on the basis of socioeconomic status and subjective social status. Often, the members of a particular social class share values and have similar cultural interests and social patterns. A popularly used classification divides individuals into an upper class, a middle class (sometimes subdivided into upper middle and lower middle classes), a working class, and people with a lower social and economic status.