Ancient Greek is the form of Greek used during the periods of time spanning c. the 9th – 6th century BC (known as Archaic), c. the 5th – 4th century BC (Classical), and c. the 3rd century BC – 6th century AD (Hellenistic) in ancient Greece and the ancient world.
Ancient Greek nouns inflect in 5 cases (nominative, genitive, dative, accusative, and vocative) and 3 numbers (singular, dual, and plural).