Where does “rōbur” come from?

rōbur (Latin) comes from Latin ruber, from Proto-Italic ruðros, from Proto-Indo-European h₁rudʰrós, from Proto-Indo-European h₁rewdʰ- — red.

Ancestry of “rōbur”, step by step

Step	Language	Word	Meaning
1	Latin	ruber	red ; ruddy
2	Proto-Italic	ruðros	red
3	Proto-Indo-European	h₁rudʰrós	red
4	Proto-Indo-European	h₁rewdʰ-	red

rōbur — Etymology, Origin & Word History | Etymology Explorer