A lingua franca is a language systematically used to communicate between persons not sharing a mother tongue, in particular when it is a third language, distinct from both persons' mother tongues.lingua franca, (Italian: “Frankish language”) language used as a means of communication between populations speaking vernaculars that are not mutually intelligible. The term was first used during the Middle Ages to describe a French- and Italian-based jargon, or pidgin, that was developed by Crusaders and traders in the eastern Mediterranean and characterized by the invariant forms of its nouns, verbs, and adjectives.
The original Lingua Franca was a mixed language composed mostly (80%) of Italian with a broad vocabulary drawn from Turkish, French, Spanish, Greek and Arabic. It was in use throughout the eastern Mediterranean as the language of commerce and diplomacy in and around the Renaissance era. At that time, Italian speakers dominated seaborne commerce in the port cities of the Ottoman empire. Franca was the Italian word for Frankish. Its usage in the term lingua franca originated from its meaning in Arabic, dating from before the Crusades, whereby all Europeans were called "Franks" or Faranji in Arabic (?). It has close resemblance to the arabic word, which literally means foreign (?). The term lingua franca is first recorded in English in 1678.