stratum

英 ['strɑːtəm; 'streɪtəm] 美['stretəm]

• n. （组织的）层；[地质] 地层；社会阶层

1. one of several parallel layers of material arranged one on top of another (such as a layer of tissue or cells in an organism)

2. an abstract place usually conceived as having depth;

"a good actor communicates on several levels"

"a simile has at least two layers of meaning"

"the mind functions on many strata simultaneously"