Apparently..
Naga from Sanskrit for "snake" or "serpent." There were serpent gods found throughout central and east Asia. For example, Naga was a serpent god that inspired a pre-Buddhhist cult in Burma. A nagini in India is a snake being (1) that is worshipped as a god and believed to be protective, including from snake bites. The second definition is along the lines of Voldemort's large female snake: (2) the Nagini were attractive female snake beings with human bodies with either have snake heads or snake coils.

