What is the meaning of Lingua_franca?

A common language used by people of diverse backgrounds to communicate with one another, often a basic form of speech with simplified grammar, particularly, one that is not the first language of any of its speakers.

Mediterranean Lingua Franca (common language spoken in Mediterranean ports in centuries past)

lingua franca (common language)

koine, lingua franca, link language, trade language, vehicular language: a common language used by people of diverse backgrounds to communicate with one another, often a basic form of speech with simplified grammar, particularly, one that is not the first language of any of its speakers.

the Mediterranean Lingua Franca, a common language spoken in Mediterranean ports in centuries past (consisting of Italian mixed with French, Spanish, Arabic and some Greek words and used by sailors of different countries to communicate with one another)

Mediterranean Lingua Franca (common language spoken in Mediterranean ports in centuries past)

lingua franca (common language)

Source: wiktionary.org