Where does “కీలక” come from?

కీలక (Telugu) comes from Sanskrit कीलक, from Sanskrit -क, from Proto-Indo-Aryan *-kas.

Ancestry of “కీలక”, step by step

Step	Language	Word	Meaning
1	Sanskrit	कीलक	a pin, bolt, wedge; a splint; a kind of tumour
2	Sanskrit	-क	doer, maker
3	Proto-Indo-Aryan	*-kas	—

కీలక — Etymology, Origin & Word History | Etymology Explorer