From the OED: 1. A cruel and oppressive ruler. 1.1 A person exercising power or control in a cruel, unreasonable, or arbitrary way. 1.2 (especially in ancien

From the OED: 1. A cruel and oppressive ruler. 1.1 A person exercising power or control in a cruel, unreasonable, or arbitrary way. 1.2 (especially in ancient Greece) a ruler who seized absolute power without legal right.