'Substratum' definitions:

Definition of 'substratum'

From: WordNet
noun
A surface on which an organism grows or is attached; "the gardener talked about the proper substrate for acid-loving plants" [syn: substrate, substratum]
noun
Any stratum or layer lying underneath another [syn: substrate, substratum]
noun
An indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population; "the Celtic languages of Britain are a substrate for English" [syn: substrate, substratum]

Definition of 'Substratum'

From: GCIDE
  • Substratum \Sub*stra"tum\, n.; pl. Substrata. [L. substratus, p. p. of substernere to strew under; sub under + sternere to strew. See Stratum.]
  • 1. That which is laid or spread under; that which underlies something, as a layer of earth lying under another; specifically (Agric.), the subsoil. [1913 Webster]
  • 2. (Metaph.) The permanent subject of qualities or cause of phenomena; substance. [1913 Webster]