

The Greek word κοινή ( koinḗ) itself means "common". The English-language name Koine is derived from the Koine Greek term ἡ κοινὴ διάλεκτος ( hē koinḕ diálektos), meaning "the common dialect". Koine Greek continues to be used as the liturgical language of services in the Greek Orthodox Church and in some Greek Catholic churches. The Roman Emperor Marcus Aurelius also wrote his private thoughts in Koine Greek in a work that is now known as The Meditations. In this context, Koine Greek is also known as "Biblical", "New Testament", "ecclesiastical", or "patristic" Greek.

Koine is also the language of the Septuagint (the 3rd century BC Greek translation of the Hebrew Bible), the Christian New Testament, and of most early Christian theological writing by the Church Fathers. Literary Koine was the medium of much post-classical Greek literary and scholarly writing, such as the works of Plutarch and Polybius.

As the dominant language of the Byzantine Empire, it developed further into Medieval Greek, which then turned into Modern Greek. Koine Greek included styles ranging from conservative literary forms to the spoken vernaculars of the time.

It was based mainly on Attic and related Ionic speech forms, with various admixtures brought about through dialect levelling with other varieties. It evolved from the spread of Greek following the conquests of Alexander the Great in the fourth century BC, and served as the lingua franca of much of the Mediterranean region and the Middle East during the following centuries. Koine Greek ( UK: / ˈ k ɔɪ n i/ KOY-nee US: / ˈ k ɔɪ n eɪ/ KOY-nay, / k ɔɪ ˈ n eɪ/ koy- NAY Koine Greek: ἡ κοινὴ διάλεκτος, romanized: hē koinè diálektos, lit.'the common dialect' Greek: ), also known as Hellenistic Greek, common Attic, the Alexandrian dialect, Biblical Greek or New Testament Greek, was the common supra-regional form of Greek spoken and written during the Hellenistic period, the Roman Empire and the early Byzantine Empire.
