Tyranny

–noun, plural -nies.
1.
arbitrary or unrestrained exercise of power; despotic abuse of authority.
2.
the government or rule of a tyrant or absolute ruler.
3.
a state ruled by a tyrant or absolute ruler.
4.
oppressive or unjustly severe government on the part of any ruler.
5.
undue severity or harshness.
6.
a tyrannical act or proceeding.

Reference: http://dictionary.reference.com/browse/tyranny