( 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; < Greekkoinḗ (diálektos) common (dialect); see ceno-2
(sometimes not capital) the Koine the Ancient Greek dialect that was the lingua franca of the empire of Alexander the Great and was widely used throughout the E Mediterranean area in Roman times