–noun (sometimes initial capital letter) (esp. in Marxist theory)
the lowest level of the proletariat comprising unskilled workers, vagrants, and criminals and characterized by a lack of class identification and solidarity.
Origin: 1920–25; < G (Marx, 1850), equiv. to Lumpen rag or Lumpen-, comb. form of Lump ragamuffin + Proletariatproletariat
lum·pen·pro·le·tar·i·at (lŭm'pən-prō'lĭ-târ'ē-ət, lŏŏm'-) n.
The lowest, most degraded stratum of the proletariat. Used originally in Marxist theory to describe those members of the proletariat, especially criminals, vagrants, and the unemployed, who lacked class consciousness.
The underclass of a human population.
[German : Lumpen, pl. of Lump, ragamuffin (from Middle High German lumpe, rag) + Proletariat, proletariat (from French prolétariat; see proletariat).]
from Marx, 1850, who used it to mean "rabble, poorest of the working class," from Ger. lump "ragamuffin" + proletariat (q.v.). Secondary sense of "boorish, stupid people" led to lumpen- being taken as a suffix meaning "unenlightened."