Where does “ستو” come from?

ستو (Hijazi Arabic) comes from Arabic سِت, from Arabic سَيِّدَة — lady.

ستو (Hijazi Arabic): grandmother

Definitions

Step	Language	Word	Meaning
1	Arabic	سِت	lady
2	Arabic	سَيِّدَة	lady

ستو — Etymology, Origin & Word History | Etymology Explorer