1) Underprivileged 
a group 'under the class structure' which is economically, politically and socially marginalised and excluded
(from the article `social class`) ...a core of chronically unemployed persons isolated from the economic mainstream in decaying urban areas. This new urban substratum of permanently ...
A class of individuals situated right at the bottom of the class system, often composed of people from ethnic minority backgrounds.
a disputed concept implying that there is a class of the population with distinctive cultural traits who are dependent on state benefits and/or poorly paid and are therefore locked into disadvantaged circumstances.
a social stratum consisting of impoverished persons with very low social status.