Definition of authoritarian:
(adj) :
of, or relating to, absolute obedience to an authority; characterised by a tyrannical obedience to an authority;
dictatorial
"the authoritarian government was demanding stricter laws against low-wage peasants."
(n) :
an
organization or
state which enforces strong or oppressive measures against its population; one who prefers, or one who enforces, absolute obedience to an authority
"michael was an authoritarian."