I know exactly how I would pronounce it, but I'm not sure how to write it. You know how you say Taj Mahal? That's the way I say Taj.
"Taj Mahal" probably means "Crown of the Palace" (literally, "Crown Palace").
Taj is the word meaning "Crown".
There's an alternate theory, but I'll let Wikipedia's article explain it:
http://en.wikipedia.org/wiki/Taj_Mahal. Be sure to follow the link to Mumtaz Mahal's bio for more on the lady who inspired the Taj Mahal.
Miranda