Autocracy

noun the principle or practice of a political system in which unrestricted power is vested in a monarch, dictator, etc.

• Absolutism refers to a political theory that advocates for the concentration of power in a single ruler.
• Some people believe absolutism is necessary for effective governance.
• I don't buy into the whole absolutism thing, I think power should be shared.
• In the realm of art, the artist's absolutism in his vision led to a masterpiece.

adjective relating to or characteristic of a system of government or control in which one person has all the power

• The monocratic leadership style of the CEO has been met with mixed reactions from the board members.
• I don't like how monocratic the new manager is - he never listens to anyone else's ideas.
• The teacher's monocratic attitude is really getting on my nerves.
• The monocratic rule of the dictator stifled any form of dissent or opposition.

noun a form of government in which a single person rules

• The country was ruled under a strict monocracy, with power centralized in the hands of one leader.
• The monocracy in that country gives all the power to one person.
• That monocracy is totally bossed by one dude.
• In nature, a beehive operates as a monocracy with the queen bee as the sole ruler.