adjective

Favouring or enforcing strict obedience to authority at the expense of personal freedom.

the transition from an authoritarian to a democratic regime

autocratic,dictatorial,totalitarian,despotic,tyrannical,autarchic,draconian,absolute,arbitrary,oppressive,repressive,illiberal,undemocratic,anti-democratic

noun

An authoritarian person.

The power structures may have changed, but authoritarians will still abuse power however they can.

autocrat,despot,dictator,tyrant,absolutist