What does sitti mean in Arabic?

Answer 1

It's in Egyptian Arabic dialect not in Standard Arabic :

Sitt = ست = woman , lady

Sitti = ستي = My lady, and also Garndmother.

Sittie= Queen or princess or anything relating royal bloods

Answer 2

Siti in Arabic means "Lady". It is a common first part of two first names e.g. "Siti Khadija".

Answer 3

Colloquial term for "grandmother" used in Syria, Lebanon, Egypt and Jordan. Possibly some other Arabic countries as well.