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)
people having the same social, economic, or educational status
a subpopulation divided into a stratified sampling
an abstract place usually conceived as having depth
A bed of earth or rock of one kind, formed by natural causes, and consisting usually of a series of layers, which form a rock as it lies between beds of other kinds. also used figuratively.
