Where does “رئیس” come from?

رئیس (Persian) comes from Arabic رَئِيس, from Proto-Semitic raʾš- — head.

رئیس (Persian): president; chief; head

Definitions

Step	Language	Word	Meaning
1	Arabic	رَئِيس	head, chief, leader; leader, chief, head
2	Proto-Semitic	raʾš-	head

رئیس — Etymology, Origin & Word History | Etymology Explorer