lower classes

Từ điển Oxford Advanced Learner 8th

the ˌlower ˈclasses f120 [lower class lower classes] BrE NAmE noun plural (also the ˌlower ˈclass singular)
the groups of people who are considered to have the lowest social status and who have less money and/or power than other people in society
compare ↑upper class
Derived Word: ↑lower class
See also: ↑lower class