Synonyms for Autocratic (same or very similar meaning)
WordNet sense 1 (offensively self-assured or given to exercising usually unwarranted power):
bossy, magisterial, peremptory, dominating, high-and-mighty
WordNet sense 2 (tending to domineer):
domineering
WordNet sense 3 (characteristic of an absolute ruler or absolute rule; having absolute sovereignty):
authoritarian, despotic, dictatorial, tyrannical
WordNet sense 4 (not in agreement with or according to democratic doctrine or practice or ideals):
undemocratic
From the ODE community, based on WordNet
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