Where does “rucio” come from?

rucio (Old Spanish) comes from Vulgar Latin roscidare, from Latin rōscidus, from Latin -idus, from Proto-Italic *-iðos.

Ancestry of “rucio”, step by step

Step	Language	Word	Meaning
1	Vulgar Latin	roscidare	—
2	Latin	rōscidus	—
3	Latin	-idus	tending to
4	Proto-Italic	*-iðos	—

rucio — Etymology, Origin & Word History | Etymology Explorer