The Bourgeoisie is the Middle and in some cases upper classes in capitalism. These are the guys who are responsible for Worker Exploitation, Low Quality Products for high prices, monopolies, low quality life style, authoritarianism, inequality of resources, and in general inequality. The Word in Français(French) is Middle Class (The Word Comes From Français), this is because in some cases, especially when the term was created, the aristocracy was considered higher power as they often had government power or other positions of power, though the Bourgeoisie often has big influence on these people.
An individual part of, relating to, or supporting the Bourgeoisie is know as a Bourgeois. It can be used sometimes as both a noun and an adjective.
The opposite of Bourgeoisie and Aristocrat is the Proletariat, this is the working class which is exploited by the Bourgeoisie.