Where does “radix” come from?

radix (Latin) comes from Proto-Italic wrādīks, from Proto-Indo-European wréh₂ds — root.

Ancestry of “radix”, step by step

Step	Language	Word	Meaning
1	Proto-Italic	wrādīks	—
2	Proto-Indo-European	wréh₂ds	root

radix — Etymology, Origin & Word History | Etymology Explorer