Lingua franca

Language used to facilitate communication between groups without a common native language

A lingua franca, also known as a bridge language, common language, trade language, auxiliary language, or link language, is a language systematically used to make communication possible between groups of people who do not share a native language or dialect, particularly when it is a third language that is distinct from both of the speakers' native languages.

This keyword could refer to multiple things. Here are some suggestions: