n.
Pronunciation: ' str ā -t ə m, ' stra-
Function: noun
Inflected Form: plural stra · ta \ ' str ā -t ə , ' stra- \
Etymology: New Latin, from Latin, spread, bed, from neuter of stratus, past participle of sternere to spread out ― more at STREW
Date: 1599
1 : a bed or layer artificially made
2 a : a sheetlike mass of sedimentary rock or earth of one kind lying between beds of other kinds b : a region of the sea or atmosphere that is analogous to a stratum of the earth c : a layer of tissue <deep stratum of the skin> d : a layer in which archaeological material (as artifacts, skeletons, and dwelling remains) is found on excavation
3 a : a part of a historical or sociological series representing a period or a stage of development b : a socioeconomic level of society comprising persons of the same or similar status especially with regard to education or culture
4 : one of a series of layers, levels, or gradations in an ordered system < strata of thought>
5 : a statistical subpopulation
usage The plural strata has occas. been used as a singular since the 18th century and is sometimes given the plural stratas <there was a strata of Paris which mere criticism of books fails to get hold of ― Ezra Pound> <a Roman burial ground suggests stratas of corruption and decay ― Connie Fletcher, Booklist >. Current evidence shows senses 2, 3b, and 4 so used, with 3b the most common. Singular strata is persistent but not frequent. Strata may someday establish itself as a singular like agenda, but that use is still not established.