Where does “geniculo-” come from?

geniculo- (English) comes from Latin geniculatus, from Latin geniculum, from Latin -culus, from Proto-Italic *-kelos.

Ancestry of “geniculo-”, step by step

Step	Language	Word	Meaning
1	Latin	geniculatus	knotty
2	Latin	geniculum	knee; little knot
3	Latin	-culus	Alternative form of -ulus; added to a noun to...
4	Proto-Italic	*-kelos	—

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