General term for a person without noble or aristocratic status, used in historical and modern contexts.
He came from a commoner background but worked hard and became a minister.
commoner (historical Japanese class)
Specifically refers to the lowest of the three social classes in Japan between 1869 and 1947, under the 族称 system.
See also: 族称
In the Meiji era, commoners were placed below the peerage and former samurai classes.
He was born a commoner but worked hard to become a government official.
That family committed a crime and were demoted to commoner status.
民衆 emphasizes the masses as a political or social collective, whereas 平民 focuses on individual status as a non-noble.
平民 is a historical/legal class term for commoners under a rank system, while 徒人 is a more literary word for an untitled individual.
Compound of 平 (へい, 'ordinary') and 民 (みん, 'people'). The historical class sense is a specific Meiji-era legal usage.