1. (

• stratum

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

2. (

• class ,
• stratum ,
• social_class ,
• socio-economic_class

) people having the same social, economic, or educational status; "the working class"; "an emerging professional class" ;

3. (

• level ,
• layer ,
• stratum

) 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" ;

4. (

• stratum ,

) a subpopulation divided into a stratified sampling ;