Koiné language

A koiné language, koiné dialect, or simply koiné (Ancient Greek κοινή, "common [language]") is a standard language or dialect made by people who speak closely related languages or dialects in order to be able to talk and write to each other easily. They are created by combining phonology, vocabulary, and grammar from the different dialects (or sometimes creating new words and grammar based on the same methods earlier this sentence). The name of the term comes from Koine Greek, which was a common dialect used by Greeks to talk and write to Greeks from other city states.
This is not to be confused with pidgins or creoles because those are languages that are created for people who speak unrelated, or distantly related, languages.