[{"Bold_text": "noun", "List Items": ["a layer of material, naturally or artificially formed, often one of a number of parallel layers one upon another:a stratum of ancient foundations.", "one of a number of portions or divisions likened to layers or levels:an allegory with many strata of meaning.", "Geology.a single bed of sedimentary rock, generally consisting of one kind of matter representing continuous deposition.", "Biology.a layer of tissue; lamella.", "Ecology.(in a plant community) a layer of vegetation, usually of the same or similar height.", "a layer of the ocean or the atmosphere distinguished by natural or arbitrary limits.", "Sociology.a level or grade of a people or population with reference to social position, education, etc.:the lowest stratum of society.", "Linguistics.(in stratificational grammar) a major subdivision of linguistic structure.Compare level(def17) level(def17)."]}]