high priestess

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The female head or chief proponent, as of a movement or doctrine.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A female clergyman with a higher function than a normal priestess.
• noun tarot the second trump or major arcana card in most traditional tarot decks.
• noun Wicca A third degree (sometimes forth degree) female witch in Wicca.