I've pronounced it as Flowswithdrek does. The word also seems to be related to 'cairn' (from the same root).
http://en.wikipedia.org/wiki/Chambered_cairnCheck out the pictures of the entrances, interior spaces, and layered construction. Now imagine that each rock in that "pile" has a ward to distract/trap a horror's attention. Then, in the center of the chamber - a warded magical lift, hidden stairway, etc leading to further habitation space (like the city of Derinkuyu:
http://en.wikipedia.org/wiki/Derinkuyu ).
I like to think this was the stock Theran 'template' sold to communities, maybe scaled up sometimes depending on the magic and tech the community could afford.