" stratum "

[Noun]  | "stra*tum" | \ ˈstrā-təm \

1: a bed or layer artificially made

2: a sheetlike mass of sedimentary rock or earth of one kind lying between beds of other kinds

3: a region of the sea or atmosphere that is analogous to a stratum of the earth

Origin: 1599 ;

 New Latin, from Latin, spread, bed, from neuter of stratus, past participle of sternere to spread out {mat|strew|};

[Noun]  | "stratum cor*ne*um" | \ -ˈkȯr-nē-əm \

1: the outermost layer of the epidermis that consists of keratin-rich corneocytes connected by desmosomes and embedded in a matrix of lipids (such as ceramides and cholesterol) arranged in bilayers and that regulates skin permeability, maintains hydration, provides structural integrity, and acts as a protective barrier (as against UV radiation, pathogens, and toxins)

Origin: 1857 ;

 New Latin, literally, horny layer;

[Noun]  | "stratum"