Synonyms for Dictatorial (same or very similar meaning)
WordNet sense 1 (likened to a dictator in severity):
authoritarian
WordNet sense 2 (not inclined to grant permission; severe in discipline):
unpermissive
WordNet sense 3 (expecting unquestioning obedience):
overbearing
WordNet sense 4 (tending to domineer):
domineering
WordNet sense 5 (characteristic of an absolute ruler or absolute rule; having absolute sovereignty):
autocratic, despotic, tyrannical
WordNet sense 6 (not in agreement with or according to democratic doctrine or practice or ideals):
undemocratic
From the ODE community, based on WordNet
add/edit