Where does “αἶνος” come from?

αἶνος (Ancient Greek) comes from Proto-Indo-European h₂ey- — vital force, life, age, eternity; day, morning.

Ancestry of “αἶνος”, step by step

Step	Language	Word	Meaning
1	Proto-Indo-European	h₂ey-	vital force, life, age, eternity; day, morning

αἶνος — Etymology, Origin & Word History | Etymology Explorer