Oh,I should have imagined that Sathanas is Greek,since you use Satan and the Italian is Satana,it must have been in Greek/Latin.
I would have asked my mother about that since she has studied Greek,but asking her something about the Devil is...not definitely ok.

Gobber:I said that probably it was Greek,
probably.DH
The plural of Colossus is Colossi,it's Latin but for a coincidence is Italian too 
I don't think that's a coincidence. Don't most European languages have their deepest roots in Latin?
There's that "Italiannenssnessness" thread in Hard Light,if you need something.