We know what authoritarianism is.

Do we? A lot of people think it's when one guy controls everything. In reality, autocracies have hella internal dynamics and quite often exercise less control than a democracy would over a given thing as a result. There's also people that think having to take simple measures to avoid spreading plagues is authoritarian, and people who think entirely removing due process isn't.

To actually answer: It depends on context, because it's not really an ideology in itself. It can mean opposing existing autocracies, or it can mean opposing more mechanisms of control, perhaps in the fear it will eventually lead to an autocracy. Sometimes it just means that the person wants to not have to do anything.

Pure political bs.

A terribly long winding word, with too many a's and i's and r's.

You can't make me tell you.

Anarchism

Depends on how you define "opposite". I'm thinking direct democracy or anarchy.

Egalitarianism.

Freedom.

A government that works for the people.

A person who is against authoritarianism.

Leftism.

Antidisestablishmentarianism but against Nazis instead of the Church of England.

When you get into political words, it's helpful to go read George Orwell.

Politics and the English Language

The opposite of authoritarian extremism is probably libertarian extremism

It's whatever I tell you it is! If you want to be anti-authoritarian, you better get in line!

Some sort of obsession for unnecessary words