Where does “χαλάζιον” come from?

χαλάζιον (Koine Greek) comes from Ancient Greek χάλαζα, from Proto-Indo-European gʰlh₂-d- — hail; hoarfrost.

Ancestry of “χαλάζιον”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	χάλαζα	hail, sleet; pimple, tubercle; knot, lump
2	Proto-Indo-European	gʰlh₂-d-	hail; hoarfrost

χαλάζιον — Etymology, Origin & Word History | Etymology Explorer