authoritarianism
Political principle or system where power is concentrated in a single authority, often with limited political freedoms.
That country has an authoritarian system.
独裁主義 emphasizes dictatorship by a single ruler, while 権力主義 is a broader term for authoritarian governance that may not be a one-person dictatorship.
全体主義 (totalitarianism) implies total state control over all aspects of life, whereas 権力主義 focuses on the concentration of power without necessarily controlling every aspect.
Compound of 権力 (power, authority) and 主義 (principle, -ism). A straightforward modern political term.