Other forms: lowlifes
A lowlife is a disreputable person living among petty criminals. A pack of lowlifes, some lowlife stole it, hang around with lowlifes.
It is a contemptuous word and a moral judgement rather than a description of income, so nobody applies it to themselves. Low life as two words is a different thing: a way of describing a whole world, as in the low life of the docks.
1nounlowlifeA disreputable person who lives among petty criminals.
“He started hanging around with drug dealers and other lowlifes.”
lowlife is a person.
Low plus life, an American formation of the twentieth century.
From low + life.
Etymology from Wiktionary, CC BY-SA