Where does “Οκτώβρης” come from?

Οκτώβρης (Greek) comes from Byzantine Greek Ὀκτώβρης, from Ancient Greek Ὀκτώβριος, from Latin octōber, from Latin octō, from Proto-Italic oktō, from Proto-Indo-European oḱtṓw, from Proto-Indo-European aḱ- — sharp, pointed; sharp, pointed, edgy; sharp,...