Government by a single person
A). Monarchy
B). Autocracy
C). Plutocracy
D). Aristocracy
Autocracy
One word substitute is Autocracy.
Monarchy: a form of government with a monarch at the head.
Autocracy: a system of government by one person with absolute power.
Plutocracy: government by the wealthy.
Aristocracy: a form of government in which power is held by the nobility.