lingua_franca
1. [ noun ] (linguistics) a common language used by speakers of different languages
Synonyms: interlingua koine interlanguage
Examples:

"Koine is a dialect of ancient Greek that was the lingua franca of the empire of Alexander the Great and was widely spoken throughout the eastern Mediterranean area in Roman times"

Related terms: language natural_language
2. [ noun ] (linguistics) a common language used by speakers of different languages
Synonyms: koine
Related terms: interlanguage