noun
Refers to the social class between the upper and working classes, often in political or historical contexts. 市民階級 can carry a nuance of 'citizen class' or 'burgher class'.
19世紀のヨーロッパでは、市民階級が政治的な力を持つようになった。
In 19th-century Europe, the middle class came to hold political power.
彼は市民階級の出身だが、今は裕福な実業家だ。
He comes from a middle-class background, but now he is a wealthy businessman.