Describes a person, attitude, or system that imposes authority without allowing dissent; often carries a negative connotation.
His subordinates pushed back against his authoritarian attitude.
That country has an authoritarian political system.
高圧的 describes a coercive, high-handed manner, often in interpersonal situations; 権威的 is broader and can refer to systems or attitudes that demand obedience based on authority.
Compound of 権威 (authority) + 的 (-like, -ish). The base noun 権威 is a Sino-Japanese word from Middle Chinese elements meaning 'power' and 'prestige'.