lumpenproletariat

(lŭmˌpən-prōˌlĭ-târˈē-ət, lo͝omˌ-)

1. 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.
2. The underclass of a human population.