stra·tum / ˈstrātəm; ˈstra-/ • n. (pl. stra·ta / ˈstrātə; ˈstra-/ ) 1. a layer or a series of layers of rock in the ground: a stratum of flint. ∎  a thin layer within any structure: thin strata of air.2. a level or class to which people are assigned according to their social status, education, or income: members of other social strata. ∎  Statistics a group into which members of a population are divided in stratified sampling.

stratum (pl. strata) Lithological term applied to rocks that form layers or beds. Unlike ‘bed’, ‘stratum’ has no connotation of thickness or extent and although the terms are sometimes used interchangeably they are not synonymous.

stratum(pl. strata) A layer of rock; unlike ‘bed’, ‘stratum’ has no connotation of thickness or extent and, although the terms are sometimes used interchangeably, they are not synonymous.

stratum (strah-tŭm) n. a layer of tissue or cells, such as any of the layers of the epidermis. s. corneum the outermost layer of the epidermis.

Stratum

one of a number of layers, 1902.

Examples : stratum of society, 1850; of mythological thought, 1870; the lower social stratum, 1902.