Strā'tum, n.
n.; Eng. pl. STRĀ'TUMS; Lat. pl. STRĀ'TȦ. The latter is more common. [Lat., from sternere, stratum, to spread.]
Sense 1. (Geol.) A bed of earth or rock of any kind, formed by natural causes, and consisting usually of a series of layers. Dana.
Sense 2. A bed or layer artificially made.