Where does “riso” come from?

riso (Old Portuguese) comes from Latin rīsus, from Ancient Greek ὄρυζα, from Proto-Iranian *wrinǰiš.

Ancestry of “riso”, step by step

Step	Language	Word	Meaning
1	Latin	rīsus	—
2	Ancient Greek	ὄρυζα	rice
3	Proto-Iranian	*wrinǰiš	—