Cruel, unjust, and absolute in power; ruling with force without concern for others' rights or feelings.
From Greek 'tyrannos' (absolute ruler, originally non-pejorative). The negative connotation developed in Ancient Greece when democratic ideals emerged and tyranny was seen as the opposite.
Ancient Athens invented democracy partly as a reaction to tyrants, and then made 'ostracism' a law to exile any leader gaining too much power—showing they learned that tyranny creeps in gradually.
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