1. A language that has been developed by the learners of a second language who have not fully acquired it, but only approximated to it, preserved some features of their first language in speaking or writing the target language, and created innovations. An interlanguage can be spoken by a small group of people, but it can also become a mass phenomenon. It can fossilize in any of its developmental stages.

2. A language that is used by speakers of different languages in order to be able to mutually communicate.