Where does “ἄλγητικός” come from?

ἄλγητικός (Ancient Greek) comes from Ancient Greek ἀλγεῖν — have pain.

Ancestry of “ἄλγητικός”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἀλγεῖν	have pain

ἄλγητικός — Etymology, Origin & Word History | Etymology Explorer