Amir (pronounced ah-MEER) means "prince" in Chammuri. The amir rules over the city of Chammur, which is on the eastern border of Sotat. The current amir's aunt was Zenadia doa Attaneh, who committed suicide rather than face the consequences for her crimes, as well as to keep her family's dignity intact.
The amir is only mentioned in Street Magic and does not appear.
Real life connections
Amir is a real word outside of the Circle Universe, and means prince in Arabic.