Where does “πᾶν” come from?

πᾶν (Ancient Greek) comes from Ancient Greek ὀπτικός, from Ancient Greek ὄψις, from Ancient Greek ὄψ, from Proto-Hellenic wókʷs, from Proto-Indo-European wekʷ- — to speak, to sound out.

πᾶν (Ancient Greek): neuter nominative singular of πᾶς; neuter...