Stra"tum (?), n.; pl. E. Stratums (#), L. Strata (#). The latter is more common. [L., from sternere, stratum, to spread; akin to Gr. &?; to spread, strew. See Strew, and cf. Consternation, Estrade, Prostrate, Stratus, Street.] 1. (Geol.) 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.

2. A bed or layer artificially made; a course.

Stra"tum (?), n.; pl. E. Stratums (#), L. Strata (#). The latter is more common. [L., from sternere, stratum, to spread; akin to Gr. &?; to spread, strew. See Strew, and cf. Consternation, Estrade, Prostrate, Stratus, Street.] 1. (Geol.) 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.

2. A bed or layer artificially made; a course.

• One of several parallel horizontal layers of material arranged one on top of another
  
• (geology) A layer of sedimentary rock having approximately the same composition throughout
  
• Any of the regions of the atmosphere, such as the stratosphere, that occur as layers
  
• (biology) A layer of tissue
  
• A class of society composed of people with similar social, cultural, or economic status