Dictionary.com/Word of the Day Archive/potentate
potentate \POH-tuhn-tayt\, noun:
One who possesses great power or sway; a ruler, sovereign, or monarch.
The shah of Persia, although he had to acknowledge that the sultan was a worthy rival, still considered himself a mighty potentate, as did the sultan himself.
-- Olivier Bernier, The World in 1800
How can he run the operation, an industry potentate wonders, "when the operations people don't report to him?"
-- "Michael Mouse", Time, August 28, 1995
After the capture of Tunis, the Emperor passed through Paris with the consent of his brother-in-law, King Francis, who wanted to present him with something worthy of so great a potentate.
-- Benvenuto Cellini, Autobiography
Potentate derives from Late Latin potentatus, "a powerful person," from Latin potentatus, "power, especially political power; supremacy," from potens, "able, powerful," from posse, "to be able." It is related to potent, "powerful," and potential, "having possibility or capability."
Dictionary.com Entry and Pronunciation for potentate