Where does “flexor” come from?

flexor (Latin) comes from Latin flecto, from Proto-Italic flektō.

Ancestry of “flexor”, step by step

Step	Language	Word	Meaning
1	Latin	flecto	I bend, curve or bow; I turn or curl; I persuade,...
2	Proto-Italic	flektō	—

flexor — Etymology, Origin & Word History | Etymology Explorer