Tyr·an·nize v. i. [imp. & p. p. Tyrannized p. pr. & vb. n. Tyrannizing ] To act the tyrant; to exercise arbitrary power; to rule with unjust and oppressive severity; to exercise power over others not permitted by law or required by justice, or with a severity not necessary to the ends of justice and government; as, a prince will often tyrannize over his subjects; masters sometimes tyrannize over their servants or apprentices.