stratum: Meaning and Definition of

stra•tum

1. a layer of material, naturally or artificially formed, often one of a number of parallel layers one upon another: a stratum of ancient foundations.
2. one of a number of portions or divisions likened to layers or levels: an allegory with many strata of meaning.
3. a single bed of sedimentary rock, generally consisting of one kind of matter representing continuous deposition.
4. a layer of tissue; lamella.
5. (in a plant community) a layer of vegetation, usually of the same or similar height.
6. a layer of the ocean or the atmosphere distinguished by natural or arbitrary limits.
7. a level or grade of a people or population with reference to social position, education, etc.: the lowest stratum of society.
8. (in stratificational grammar) a major subdivision of linguistic structure. Cf.(def. 18).