interlanguage

noun3

1. •
   A language generated by a student of a foreign language that incorporates aspects of their native language and the target language.

   • Trasyanka and Surzhyk are interlanguages: a Belarusian–Russian and a Ukrainian–Russian mixed language.
2. •
   A lingua franca, a common language used by speakers of different languages

   • Latin used to be the European interlanguage. Currently English widely serves this purpose.
3. •
   A pidgin or creole