Pronunciation: (sub'strā"tum, -strat"um, sub-strā'tum, -strat'um),[key] —n., —pl.-stra•taPronunciation: (-strā"tu, -strat"u, -strā'tu, -strat'u),[key]- stra•tums. 1. something that is spread or laid under something else; a stratum or layer lying under another.
2. something that underlies or serves as a basis or foundation.
3. Agric.the subsoil.
4. Biol.the base or material on which a nonmotile organism lives or grows.
5. Philos.substance, considered as that which supports accidents or attributes.
6. Photog.a layer of material placed directly on a film or plate as a foundation for the sensitive emulsion.
7. Historical Ling.a set of features of a language traceable to the influence of an earlier language that it has replaced, esp. among a subjugated population: The French word for 80, quatre-vingts (“four twenties”), may reflect a Celtic substratum. Cf. superstratum.