Where does “πυρο-” come from?

πυρο- (Ancient Greek) comes from Ancient Greek πῦρ, from Proto-Indo-European péh₂wr̥ — bonfire; spelt.

Ancestry of “πυρο-”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	πῦρ	a fire; lightning; a fever
2	Proto-Indo-European	péh₂wr̥	bonfire; spelt

πυρο- — Etymology, Origin & Word History | Etymology Explorer