Stratum (linguistics)
（重定向自Substratum）
In linguistics, a stratum (Latin for "layer") or strate is a language that influences, or is influenced by another through contact. A substratum or substrate is a language which has lower power or prestige than another, while a superstratum or superstrate is the language that has higher power or prestige. Both substratum and superstratum languages influence each other, but in different ways. An adstratum or adstrate refers to a language that is in contact with another language in a neighbor population without having identifiably higher or lower prestige. The notion of "strata" has first been developed by the Italian linguist Graziadio Isaia Ascoli (1829–1907), and became known in the English-speaking world by two different authors in 1932.