Where does “اجتماعی” come from?

اجتماعی (Persian) comes from Arabic اِجْتِمَاعِيّ.

اجتماعی (Persian): social; companionable

Definitions

Step	Language	Word	Meaning
1	Arabic	اِجْتِمَاعِيّ	—

اجتماعی — Etymology, Origin & Word History | Etymology Explorer