It could be the name of the place, but I doubt it was the name of the location, since when the Old Gods came, it was a primordial Azeroth with no smart races. And I doubt the Elemental Lords named lands or had some geographical needs.
If it was a place, it would be a city. And there wasn't big Old God cities known pre-Black Empire era, except the city that Xal'Atath has mentioned, described by the word "grandeur".
So K'Tanth could be a city, but the name seems close to C'Thun, and the meaning in ancient Greek could be more related to an organic being than a city.
I've been reading about Nyarlatothep, and it hits me now:
It's a thing that can take human shape, walk the earth, friendly, manipulate people for his own agenda or Outer Gods' agenda. He looks like an egyptian Pharaoh.
Ok wait, we know somebody like that: Wrathion
Is he related to N'yalotha ?