Petite bourgeoisie (French pronunciation: [pətit buʁʒwazi]), also petty bourgeoisie (literally small bourgeoisie), is a French term (sometimes derogatory) referring to a social class comprising semi-autonomous peasantry and small-scale merchants whose politico-economic ideological stance is determined by reflecting that of a haute (high) bourgeoisie, with which the petite bourgeoisie seeks to identify itself, and whose bourgeois morality it strives to imitate.
The term is politico-economic, and references historical materialism. It originally denoted a sub-stratum of the middleclasses in the 18th and early-19th centuries. In the mid-19th century, the pre-eminient theorist of socio-politico-economy, Karl Marx, and other Marxist theorists used the term petite bourgeoisie to identify the socio-economic stratum of the bourgeoisie that comprised small-scale capitalists such as shop-keepers and workers who manage the production, distribution, and/or exchange of commodities and/or services owned by their bourgeois employers.
The petite bourgeoisie are economically distinct from the proletariat and the lumpenproletariat, who are social-class strata who entirely rely on the sale of their labor-power for survival; and also are distinct from the capitalist class haute bourgeoisie (high bourgeoisie) who own the means of production, and thus can buy the labor-power of the proletariat and lumpenproletariat to work the means of production. Though the petite bourgeoisie can buy the labor of others, unlike the haute bourgeoisie, they typically work alongside their employees; and, although they are business owners, they do not own a controlling share of the means of production. The means of production owned by the petite bourgeoisie do not generate enough revenue surplus value to permit the accumulation of capital to be reinvested into production; unless they take extreme financial chances.
Historically, Karl Marx predicted that the petite bourgeoisie were to lose in the course of economic development. In the event, R. J. B. Bosworth suggested that they were to become the political mainstay of Fascism, which political reaction was their terroristic response to the inevitable loss of power (economic, political, social) to the haute bourgeoisie.
^Habermas  Technology and Science as Ideology quotation:
... Their socialization seems to have been achieved in subcultures freed from immediate economic compulsion, in which the traditions of bourgeois morality and their petit-bourgeois derivatives have lost their function.