What term did Karl Marx use to refer to the working class?

Karl Marx used the term "proletariat" to specifically refer to the working class in his analysis of society and economics. In Marxist theory, the proletariat is the class of individuals who do not own the means of production and are therefore dependent on selling their labor for wages. This concept is central to Marxist ideology, as he believed that the proletariat would eventually rise up against the bourgeoisie, who are the owners of the means of production, leading to a revolution that would establish a classless society.

The other terms listed, while related to class and labor, do not capture the specific sociopolitical context that Marx emphasized. The term "bourgeoisie" refers to the capitalist class who own the means of production and exploit the labor of the proletariat. "Working class" is a more general term that can describe all individuals engaged in manual labor or trade, but does not carry the same historical and theoretical weight in Marx's work. "Laborers" is similar to "working class" but is also a broader term that does not specifically denote the socio-economic struggle or class conflict highlighted in Marxist theory. Understanding the distinction between these terms is vital for grasping the foundational concepts of Marx's critique of capitalism.