Where does “πενταέτηρος” come from?

πενταέτηρος (Ancient Greek) comes from Ancient Greek ἔτος, from Ancient Greek ϝέτος, from Proto-Indo-European wétos, from Proto-Indo-European wet- — year; year-old.

Ancestry of “πενταέτηρος”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἔτος	year
2	Ancient Greek	ϝέτος	—
3	Proto-Indo-European	wétos	year
4	Proto-Indo-European	wet-	year; year-old

Every word from Proto-Indo-European wet- →Every word from Proto-Indo-European wétos →Every word from Ancient Greek ϝέτος →