1. Coptic substratum
If substratal influence is understood as “imperfect group learning during a process of language shift” (Thomason and Kaufman 1988:38), it has to be dealt with separately from ‘loanwords’ which are simply ‘borrowings’ (Thomason and Kaufman 1988:20ff.). On the phonological level, there is no evidence for Coptic substratal influence. It is true that in all Egyptian Arabic dialects the interdentals have merged with plosives, a phenomenon to be observed on a large geographical s…