a Greek dialect that flourished under the Roman Empire
a common language used by speakers of different languages
"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"
A lingua franca.
The “common” Greek language that developed and flourished between 300 B.C.E. and 300 C.E. (the time of the Roman Empire), and from which Modern Greek descended. It was based on the Attic and Ionian dialects of Ancient Greek.