substratum

noun

1. a surface on which an organism grows or is attached

   noun.location

   Synonyms substrate

   Source: WordNet 3.0

2. any stratum or layer lying underneath another

   noun.location

   Source: WordNet 3.0

3. an indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population

   noun.communication

   Source: WordNet 3.0

4. That which is laid or spread under; that which underlies something, as a layer of earth lying under another; specifically <i>(Agric.)</i>, the subsoil.

   noun

   Source: webster1913