Broadly speaking, there are two sources of interference in Arabic, one extraneous and one indigenous, affecting both the spoken and written forms of the language. Extraneous interferences come from the foreign languages with which speakers of Arabic come into contact. Indigenous interferences come from local spoken varieties of Arabic and the written form of the language itself. Contact interference is not uncommon in other languages. In the case of Arabic, however, the matter is more complex, owing to factors peculiar to the language and region itself.

Arabic has been in contact…