Dictator

Part of speech: noun (n.)

1. One who dictates; one who prescribes rules and maxims authoritatively for the direction of others. Locke.

2. One invested with absolute authority; especially, a magistrate created in times of exigence and distress, and invested with unlimited power. Invested with the authority of a dictator, nay, of a pope, over our language. Macaulay.