Where does “маи́с” come from?

маи́с (Russian) comes from Spanish maíz, from Taíno mahís, from Proto-Arawakan marikɨ.

Ancestry of “маи́с”, step by step

Step	Language	Word	Meaning
1	Spanish	maíz	corn, maize
2	Taíno	mahís	—
3	Proto-Arawakan	marikɨ	—