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.
- A horizontal layer of material, especially one of several parallel layers arranged one on top of another.
- Geology A bed or layer of sedimentary rock having approximately the same composition throughout.
- Any of the regions of the atmosphere, such as the troposphere, that occur as layers.
- Biology A layer of tissue: the epithelial stratum.
- A level of society composed of people with similar social, cultural, or economic status.
- One of a number of layers, levels, or divisions in an organized system: a complex poem with many strata of meaning.