stratum

1. N-COUNT A stratum of society is a group of people in it who are similar in their education, income, or social status. 社会阶层[正式] [usu with supp]

It was an enormous task that affected every stratum of society. 这是一项影响到社会各阶层的重大任务。

2. N-COUNT Strata are different layers of rock. 岩层[技术] [usu pl]

Contained within the rock strata is evidence that the region was intensely dry 15,000 years ago. 岩层中的证据表明该地区在15,000 年前曾经非常干旱。