Bourgeoisie is a term used in classical Marxism for the social class that controls the means of production. In opposition to the proletariat class, who earn income from the sale of their labor, the bourgeoisie class generates income through the processes of capital.
In its wider sense it means those of the middle class, originally neither aristocratic nor peasant and was the French equivalent of Burgess (English) or Burgher (German). All were citizens or freemen of the medieval burgh or town from whence we get the modern "Borough". By extension, the adjective "bourgeois" can mean hum-drum, unimaginative, conventional and the like.