ty·rant / ˈtīrənt/ • n. 1. a cruel and oppressive ruler: the tyrant was deposed by popular demonstrations. ∎  a person exercising power or control in a cruel, unreasonable, or arbitrary way: her father was a tyrant and a bully. ∎  (esp. in ancient Greece) a ruler who seized power without legal right.2. a tyrant flycatcher.

tyrant absolute ruler; despotic ruler. XIII. — OF. tyrant, tiran (mod. tyran) — L. tyrannus — Gr. túrannos. (OF. tyrant is analogical after forms in -ANT.)
So or hence tyrannic XV. — (O)F. tyrannical XVI. tyrannous XV. tyranny XIV. — (O)F. tyrannie — late L. tyrannia — Gr. turanníā. tyrannize XV. — (O)F. tyranniser.