In a political context - In favor of large, intrusive government that violates or suppresses individual rights; characterized by a "law and order" approach; failing to support civil liberties and/or economic freedom in society; undemocratic
In a non-political context - Bossy, controlling, domineering
People with authoritarian views, agendas, or personalities rarely describe themselves as authoritarian, but can often be spotted when they try to rationalize some government control as being necessary "for national security", "for public safety", "for the children", or "for your own good".
The longer Senator Bullwrap stayed in office, the more authoritarian he became.