A form of government other than a monarchy in which the formal written constitution is not adhered to and is broken by force of arms by a single person who then undertakes to rule as a monarch and primarily in his personal interests.
McLean and McMillan highlight that tyranny and dictatorship are similar in that an essential feature of tyranny is:
"... the abuse of the state’s coercive force in the absence of the rule of law....
"(G)overnment by the rule of the tyrant and the arbitrary treatment of citizens, if not the systematic use of terror."
Most definitions of a tyranny include reference to the arbitrary or oppressive rule of the tyrant although in Greek history, there have been tyrants who, albeit interrupting forms of democracy and obtaining power by force, continued the rule of law (e.g. Pisistratus).
According to Plutarch, Solon said:
"Tyranny is indeed a very pleasant peak, but there is no way down from it."
McLean, I., and McMillan, A., Oxford Concise Dictionary of Politics, (Oxford: Oxford University Press, 2003), p. 547.