'Superstratum' definitions:

Definition of 'superstratum'

From: WordNet
noun
Any stratum or layer superimposed on another [syn: superstrate, superstratum]
noun
The language of a later invading people that is imposed on an indigenous population and contributes features to their language [syn: superstrate, superstratum]

Definition of 'Superstratum'

From: GCIDE
  • Superstratum \Su`per*stra"tum\, n.; pl. Superstrata. [NL.: cf. L. supersternere, superstratum, to spread upon. See Super-, and Stratum.] A stratum, or layer, above another. [1913 Webster]