Two Bears, you just taught me something. Most Hawaiian words use a change in article to indicate plural, for example: ka pua, the flower, na pua, the flowers. But according to my dictionary, kahuna becomes plural by adding a macron (kahakou) -- a dash -- over the first "a", stressing and lengthening it. (The "a" in the plural article na also has a kahakou.) I'm sure there are other words that make the plural that way, but I don't know them. Then again, I don't know very much Hawaiian!

It's a bit frustrating that Microsoft's special symbols fonts have all the different diacritical markings except the macron, making it difficult to type Hawaiian words on the computer.

My dictionary defines kahuna as "priest, minister, sorcerer, expert in any profession." It can also be used as a verb. Some interesting combining forms of kahuna:

kahuna 'ana'ana: sorcerer who practices black magic
kahuna kalai wa'a: canoe builder (those in the DC area will get to see a kahuna kalai wa'a on the Mall this summer, finishing a Hawaiian fishing canoe which will be donated to the Smithsonian. Details here.)
kahuna kilokilo: priest or expert who observes the skies for omens
and my favorite, kahuna lapa'au: medical practitioner (literally, "expert in healing")

Aloha,
Mark