superstrate

Superstrate is a term used in linguistics and in materials science to describe a layer or influence that sits above another layer.

In linguistics, the superstrate (often called the lexifier) is the language that provides the majority of the basic vocabulary in a pidgin or creole. It is usually associated with the socially or politically dominant community. The other languages involved are referred to as substrates and typically contribute grammatical structure, phonology, and other features. The distinction helps explain how a creole can have a vocabulary largely from one language while its grammar reflects multiple source languages. Common examples include Haitian Creole, whose lexicon is primarily French, and Tok Pisin, whose lexicon is primarily English. The exact roles of superstrate and substrate can vary across contact situations and may shift over time.

In materials science and engineering, the term denotes the layer that lies above another layer in a stratified structure. The superstrate layer can influence film growth, adhesion, and the optical, chemical, and electrical environment of the underlying substrate. This usage appears in thin-film devices, solar cells, and optical coatings, where a top layer sits on a substrate to provide protection, encapsulation, or functional properties.

Etymology: from Latin superstratum, meaning what lies above; formed from super- 'over' and stratum 'layer'. The concepts of superstrate and substrate are context-dependent but share the general idea of hierarchical layering.