Source : Webster's Revised Unabridged Dictionary (1913)

Tyrannize \Tyr"an*nize\, v. i. [imp. & p. p. {Tyrannized}; p.
   pr. & vb. n. {Tyrannizing}.] [Cf. F. tyranniser, Gr. ? to
   take the part of tyrants.]
   To act the tyrant; to exercise arbitrary power; to rule with
   unjust and oppressive severity; to exercise power 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.