Where does “ῐ̓́σος” come from?

ῐ̓́σος (Ancient Greek) comes from Ancient Greek βάρος, from Ancient Greek βαρύς, from Proto-Hellenic gʷarus, from Proto-Indo-European gʷréh₂us, from Proto-Indo-European -us — Forms adjectives from Caland system roots.

ῐ̓́σος (Ancient Greek): equal