stratum
英 ['strɑːtəm; 'streɪtəm]
美['stretəm]
	    - n. (组织的)层;[地质] 地层;社会阶层
 
英英释意
- 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"
 
