Where does “Rhodri” come from?

Rhodri (Welsh) comes from Welsh rhod, from Proto-Brythonic rrod, from Proto-Celtic rotos, from Proto-Indo-European Hret- — to roll; wheel; to run, roll.

Ancestry of “Rhodri”, step by step

Rhodri traces back through two separate lines of ancestry.

via Welsh rhod

Step	Language	Word	Meaning
1	Welsh	rhod	wheel; orb; ecliptic
2	Proto-Brythonic	rrod	wheel
3	Proto-Celtic	rotos	wheel
4	Proto-Indo-European	Hret-	to roll; wheel; to run, roll

via Welsh rhi

Step	Language	Word	Meaning
1	Welsh	rhi	king; The name of the Latin-script letter Rh
2	Middle Welsh	ri	—

Every word from Proto-Indo-European Hret- →Every word from Proto-Celtic rotos →Every word from Proto-Brythonic rrod →