Bourgeois refers to a member of the so-called middle class, sometimes defined as persons engaged in shopkeeping, merchandising, and similar pursuits. As an adjective, bourgeois means "conventional," "characterized by materialistic concerns or activities." The general meaning of bourgeois may be inferred from its origin: a burgess is, or was, a citizen who was neither of the nobility nor a serf. Proletariat refers to persons who depend for support upon employment rather than property. The word is derived from a Latin phrase referring to individuals who contributed to the state only through their offspring. In brief, bourgeois means "middle-class," and proletarian means "working-class." Most Americans do not think of themselves as being either bourgeois or proletarian.
Dictionary of problem words and expressions. Harry Shaw. 1975.