Old Greek is the Greek language as spoken from Late Antiquity (c. AD 400) to around AD 1500. Greek spoken during this period is usually split into:

• Koine Greek - also referred to as "the common dialect" or "Alexandrian dialect", "common Attic" or "Hellenistic Greek" - the universal dialect spoken throughout post-Classical antiquity (c. 300 BC – 300 AD)
• Late Greek (c. 400 – c. 800 AD)
• Medieval Greek (c. 800 – c. 1500 AD)