n. (pl. strata)
1. esp. Geol. a layer or set of successive layers of any deposited substance.
2 an atmospheric layer.
3 a layer of tissue etc.
4 a a social grade, class, etc. (the various strata of society). b Statistics each of the groups into which a population is divided in stratified sampling.
Derivatives:
stratal adj.
Etymology: L, something spread or laid down, neut. past part. of sternere strew