Merriam-Webster's Word of the Day for May 18, 2008 is:

hierophant • \HYE-uh-ruh-fant\  • noun
1 : a priest in ancient Greece; specifically : the chief priest of the Eleusinian mysteries 2 *a : a person who explains : commentatorb : a person who defends or maintains a cause or proposal : advocate

Example sentence:
"Very few women can be coerced into spending $4,000 for green leather trousers embroidered with silver petals . . . simply because some fashion hierophant declares it a trend." (Cathy Horyn, The New York Times, March 30, 1999)

Did you know?
"Hierophant," "hieroglyphics," and "hierarch" have a common root: "hieros," a Greek word meaning "sacred." "Hieroglyphics" joins "hieros" with a derivative of "glyphein," the Greek verb for "carve." "Hierarch," a word that can refer to a religious leader in a position of authority, joins "hieros" with a derivative of "archein," meaning "to rule." "Hierophant" itself joins the root with a derivative of "phainein," which means "to show." The original hierophants were priests of the ancient Greek city of Eleusis who performed sacred rites. In the 17th century, when the word was first documented in English, it referred to these priests. By the 19th century, English speakers were using the term in a broader sense. A "hierophant" can now be a spokesperson, a commentator, an interpreter, or a leading advocate.

*Indicates the sense illustrated in the example sentence.