I name my fantasy world just "World" in different languages. As I'm not a philologist or linguist, I just use existing languages in the Middle Ages to represent translations of the actual languages they use.
Quote Originally Posted by lukc
this actually replicates the way we use names in the real-world. Referring to the nearby big city as "the City", the big river becomes "the river" and so on.
You're definitively right guys. I believe Earth, Terra, ... are lately names from Galileo's times when people realized "earth" or "the world" was actually a planet like any other and they decided to name that planet somehow. In Japanese it is even more clear this is a late concept: they call it 地球, which means "earth ball".

I believe in ancient times "the world" was named "the world". Why would someone needs to find another name ? There's only one world in the mind of people then. It's obvious which one it is.

Similarly, "the moon" refers to earth's moon. "Satellite" came also later, when people observed satellites and realized the moon was a satellite like the other.