noun (n)

• a surface on which an organism grows or is attached(noun.location)

  Synonym:
  substrate
  

  source: wordnet30
• any stratum or layer lying underneath another(noun.location)

  source: wordnet30
• an indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population(noun.communication)

  source: wordnet30
• That which is laid or spread under; that which underlies something, as a layer of earth lying under another; specifically (Agric.), the subsoil.(noun)

  source: webster1913