lingua franca
/ˌlɪŋgwəˈfræŋkə/noun
(pl. lingua francas)
1- a language that is adopted as a common language between speakers whose native languages are different（不同母语的人用以作为交际语言的）通用语, 共同语。
1.1
- mass noun historical a mixture of Italian with French, Greek, Arabic, and Spanish, formerly used in the Levant〈史〉（旧时在地中海东部黎凡特地区使用的）混杂语（包括意大利语、法语、希腊语、阿拉伯语和西班牙语）。
词源
late 17th cent.: from Italian， literally 'Frankish tongue'.