I'm sure this is far too late to get voted up, but what the heck:

Chiliad [kil-ee-ad]. A rarely-seen English word meaning "a millenium" or "group of a thousand things". Both meanings used figuratively here to indicate both their vast age and the secrecy with which they shroud themselves. Also invokes the English words "kill" and "chill" for a little extra flavour. The -ad ending subtly suggests a collective (compare "triad") without spelling it out.

I think the word is unusual enough (both in rarity and pronunciation) that it sounds foreign and a little alien.