(n)an indigenous language that contributes features to the language of an invading people who impose their language on the indigenous population, Syn.substratum
The Collaborative International Dictionary of English (GCIDE) v.0.53Collaborative International Dictionary (GCIDE)
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 ]