stratum
stra.tum \'stra-t-*m, 'strat-\ \'stra-t-*, 'strat-\ n or stra.ta [NL, fr.
L, spread, bed, fr. neut. of stratus, pp. of sternere to s] pl pread out -
more at STREW 1: a bed or layer artificially made 2a: a sheetlike mass of
sedimentary rock or earth of one kind lying between beds of other kinds
2b: a region of the sea or atmosphere that is analogous to a stratum of the
earth 2c: a layer of tissue {deep ~ of the skin} 2d: a layer in which
archaeological material (as artifacts, skeletons, and dwelling remains) is
found on excavation 3a: a part of a historical or sociological series
representing a period or a stage of development 3b: a socioeconomic level
of society comprised of persons of the same or si milar status esp. with
regard to education or culture 4: one of the sets considered as an
integrated whole that make up an ordere d, layered, or superimposed group
of sets {a statistical sampline of various population strata}