Meaning

noun one of several parallel layers of material arranged one on top of another (such as a layer of tissue or cells in an organism or a layer of sedimentary rock)

noun people having the same social, economic, or educational status

noun an abstract place usually conceived as having depth

originBorrowed from Latin strātum (“a spread for a bed, coverlet, quilt, blanket; a pillow, bolster; a bed”), neuter singular of strātus, perfect passive participle of sternō (“spread”). Doublet of estrade and street.

Etymology from Wiktionary, CC BY-SA 3.0