tyranny

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A government in which a single ruler is vested with absolute power.
2. n. The office, authority, or jurisdiction of an absolute ruler.
3. n. Absolute power, especially when exercised unjustly or cruelly: "I have sworn . . . eternal hostility against every form of tyranny over the mind of man” ( Thomas Jefferson).
4. n. Use of absolute power.
5. n. A tyrannical act.
6. n. Extreme harshness or severity; rigor.

Century Dictionary and Cyclopedia

1. n. The rule of a tyrant in the ancient sense; the personal government of one of the Greek tyrants; a state or government having an uncontrolled ruler bearing the title of tyrant.
2. n. The office or incumbency of a tyrant; a tyrant's administration or tenure; the system of government by tyrants.
3. n. Hence A tyrannical government; a lawless autocracy or despotism.
4. n. Arbitrary or unrestrained exercise of power; despotic abuse of anthority; unmerciful rule.
5. n. A tyrannical action or proceeding; an instance of despotic rule or conduct.
6. n. Severity; harshness; stringency.
7. n. Synonyms Despotism, Autocracy, etc. See despotism.
8. n. Oppression, Despotism, etc. See oppression.

Wiktionary

1. n. A government in which a single ruler (a tyrant) has absolute power.
2. n. The office or jurisdiction of an absolute ruler.
3. n. Absolute power, or its use.
4. n. Extreme severity or rigour.

GNU Webster's 1913

1. n. The government or authority of a tyrant; a country governed by an absolute ruler; hence, arbitrary or despotic exercise of power; exercise of power over subjects and others with a rigor not authorized by law or justice, or not requisite for the purposes of government.
2. n. Cruel government or discipline.
3. n. Severity; rigor; inclemency.

WordNet 3.0

1. n. a form of government in which the ruler is an absolute dictator (not restricted by a constitution or laws or opposition etc.)
2. n. dominance through threat of punishment and violence