The nobility is a social stratum specially defined in law.

贵族是一个拥有特定法律意义的社会阶层。

youdao

Doctors ought to belong to a social stratum with fairly high incomes.

医生应当是社会上较高收入的阶层。

youdao

A social stratum whose members share certain economic, social, or cultural characteristics.

阶层，阶级：一种社会层次，其成员有共同的经济、社会或文化特征。

youdao

Society being composed of social strata a family will find its children in competition with children from families in roughly the same social-economic stratum, with roughly the same total amount of family income to invest in children.

FORBES: Demographic Decline and Investment Intensity in Children -- Observations on China and Japan

If my children were in public school, they would spend their days in rooms with children all within a year of their own age, all from the same neighborhood and social stratum.

FORBES: Leadership Takes Many Forms - Like A 13-Year-Old Lecturer In A Ski Cap