Definition of the word Svaha - I've heard from multiple sources that
it's a native american word it that means the 'Time between when you
see the lightning and hear the thunder' but can't find an official
reference. Charles De Lint references this word in his book by the
same title but just says it's a native american word. I've e-mailed
him and he said it was a native american word but he doesn't remember
what tribe (and it's been so long since he wrote the book the threw
out his notes).  I'm not looking for the Hindi goddess reference, just
the ligtning/thunder reference above. I've googled the hell out of
this and have been looking for a real reference to cite for over 10
years. Help me Obi Wan Kenobi, you're my only hope.

Here's a page which attributes the word to the Dineh (Navajo)
language, but admits that this is unverified:

"svaha [attrib. to Dineh (Navajo); provenance unverified]"

http://richter.colorado.edu/~sethmc/words.html