Nouns

(n)stratumone 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)
(n)class, stratum, social class, socio-economic classpeople having the same social, economic, or educational status“the working class”, “an emerging professional class”
(n)level, layer, stratuman 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”
(n)stratuma subpopulation divided into a stratified sampling