Where does “coxus” come from?

coxus (Latin) comes from Latin coxa, from Proto-Indo-European koḱs- — joint.

Ancestry of “coxus”, step by step

Step	Language	Word	Meaning
1	Latin	coxa	hip , hipbone; thigh
2	Proto-Indo-European	koḱs-	joint

coxus — Etymology, Origin & Word History | Etymology Explorer