Tunisian, or Tunisian Arabic (تونسي Tounsi local pronunciation: [ˈtuːnsi] or دارجة dèrja [ˈdɛːrʒæ]) is a Maghrebi dialect of the Arabic language, spoken by some 11 million people in coastal Tunisia. It is usually known by its own speakers as Derja, which means dialect, to distinguish it from Standard Arabic, or as Tunsi, which means Tunisian. In the interior of the country it merges, as part of a dialect continuum, into Algerian Arabic and Libyan Arabic. Its morphology, syntax, pronunciation and vocabulary are quite different from Standard or Classical Arabic. Tunisian Arabic, like other Maghrebi dialects, has a vocabulary mostly Arabic, with significant Berber substrates, and many words and loanwords borrowed from Berber, French, Turkish, Italian and Spanish. Derja is mutually spoken and understood in the Maghreb countries, especially Morocco, Algeria and Tunisia, but hard to understand for middle eastern Arabic speakers. It continues to evolve by integrating new French or English words, notably in technical fields, or by replacing old French and Spanish ones with Standard Arabic words within some circles; more educated and upper-class people who make code-switching between Maghrebi Arabic and Modern Standard Arabic also have more French and Spanish loanwords. Moreover, Tunisian is also closely related to Maltese, which is not considered to be a dialect of Arabic for sociolinguistic reasons.
Almost all literate speakers of Tunisian also understand and can speak some Standard Arabic. Some Tunisians view Tunisian Arabic as a derivative form of Classical Arabic with loanwords from Berber, French, Italian, Turkish and Spanish though awareness of Tunisian as a distinct language is growing, especially among the younger generation. (Wikipedia)