MIA: Encyclopedia of Marxism: Glossary of Terms
Roughly translated as slum workers or the mob, this term identifies the class of outcast, degenerated and submerged elements that make up a section of the population of industrial centers. It includes beggars, prostitutes, gangsters, racketeers, swindlers, petty criminals, tramps, chronic unemployed or unemployables, persons who have been cast out by industry, and all sorts of declassed, degraded or degenerated elements. In times of prolonged crisis (depression), innumerable young people also, who cannot find an opportunity to enter into the social organism as producers, are pushed into this limbo of the outcast. Here demagogues and fascists of various stripes find some area of the mass base in time of struggle and social breakdown, when the ranks of the Lumpenproletariat are enormously swelled by ruined and declassed elements from all layers of a society in decay.
The term was coined by Marx in The German Ideology in the course of a critique of Max Stirner. In passage of The Ego and His Own which Marx is criticising at the time, Stirner frequently uses the term Lumpe and applies it as a prefix, but never actually used the term “lumpenproletariat.” Lumpen originally meant “rags,” but began to be used to mean “a person in rags.” From having the sense of “ragamuffin,” it came to mean “riff-raff” or “knave,” and by the beginning of the eighteenth century it began to be used freely as a prefix to make a range of perjorative terms. By the 1820s, “lumpen” could be tacked on to almost any German word.