Where does “τέσσερα” come from?

τέσσερα (Ancient Greek) comes from Ancient Greek τέσσᾰρᾰ, from Ancient Greek τέσσᾰρες, from Proto-Hellenic kʷétwores, from Proto-Indo-European kʷetwóres, from Proto-Indo-European kʷe- — and.

τέσσερα (Ancient Greek): four