(usually initial capital letter) an amalgam of Greek dialects, chiefly Attic and Ionic, that replaced the Classical Greek dialects in the Hellenistic period and flourished under the Roman Empire.
2.
a lingua franca.
Origin: 1910–15; < Gk koin (diálektos) common (dialect); see ceno-2
A dialect of Greek that developed primarily from Attic and became the common language of the Hellenistic world, from which later stages of Greek are descended.
koine A lingua franca.
koine A regional dialect or language that becomes the standard language over a wider area, losing its most extreme local features.
[From Greek (hē) koinē (dialektos), common (language), feminine of koinos, common; see kom in Indo-European roots.]