kahuna /kəˈhuːnə/ n. 1. a priest, sorcerer, magician, wizard, minister, expert in any profession.
2. an individual who is can be described as a big shot. A very generic term, and there are no distinctions, i.e. a pimp can be referred to as a Big Kahuna, and so can the CEO of a Fortune 500 company.
3. American slang. Literally: big balls. Figuratively: a man who has big kahunas has a lot of nerve, is brave, a risk taker, has a lot of testosterone.