Here are some links on the Root of the word Jedi in the form of Djedi:
http://www.djedet.com/ladyjedi.php
http://bluestarenterprise.com/old-website/Jedi_Article.html
http://en.wikipedia.org/wiki/Prince_Djedi
http://en.wikipedia.org/wiki/Djedi_Project

And being of egyptian root we would look for Sith as "Set" or possibly Seth:
Here is Set also Seth:
http://ancientegyptonline.co.uk/set.html
http://www.touregypt.net/featurestories/set.htm
http://en.wikipedia.org/wiki/Set_(mythology)

I have also see the root of Jedi Possibly in the name Jedidiah* Jedi-Diah* Which means Friend of God in Hebrew. The Diah part meaning God and the Jedi part meaning friend.

So if God is in this case the force then we have friend of the force. I believe that god is just like the force as described in The Jedi path. "created by life" versus the other way around.

But Keep looking. Seeking. This is the way of The Jedi. May the force be with you!