lingua franca; vehicular language; bridge language
A language used for communication between groups that do not share a native language. Used in linguistics and sociolinguistics.
English is widely used as an international lingua franca.
In multilingual societies, a common bridge language is often necessary.
国際語 is an international language used across countries, often with official or widespread status, whereas 媒介語 focuses on the function of bridging communication.
Compound of 媒介 (ばいかい, 'mediation, intermediary') and 語 (ご, 'language'). The exact historical derivation is uncertain, but the term follows standard Sino-Japanese word formation patterns.