Where does “سيئول” come from?

سيئول (Arabic) comes from Korean 서울, from Old Korean 徐羅伐.

Ancestry of “سيئول”, step by step

Step	Language	Word	Meaning
1	Korean	서울	capital; large city
2	Old Korean	徐羅伐	—

سيئول — Etymology, Origin & Word History | Etymology Explorer