Looking over some notes from a history class to answer this question since a peer asked this of our professor. Persepolis means "Persian city" in Greek, a decent translation since the Persians called the city "Persia" or "Parsa". Both words seem to convey this cities importance in the Empire. This would be similar to what we do today with cities in other countries. English "Cologne" and German "Köln".

Edit: I understand this subreddit's need of thoroughness. I may be able to give additional references and links later if you would like. However, I just did a quick google search and one may find plenty of information.