(n) 1. A section of the population in capitalist society that is deprived of a role in production.
(n) 2. The most impoverished section in capitalist society comprising mostly of vagrants, vagabonds, criminals, welfare recipients, drug addicts, etc.
(n) 3. A non-revolutionary current in capitalist society, in Marxist terms.
A socialist revolution could never come from the lumpenproletariat due to the fact that they have no stake in production.