Let me get this straight - anything that's counter to what the Trumpists like is "fake news," and anything that Trump says is the "truth"?

Fake News is any and everything that  Trump and the Trumpsters don't agree with. In other words they prefer to believe in opinions which are not based on facts or in conspiracy theories.  Facts don't matter to both the Trumpsters and Trump.

The whole world doesn't listen to US news. That's why the world know that Biden will be US president in January and Trump is a loser.

That is correct.  The Cult Leader is always correct and any disparagement is false. 

Anonymous Coward below:  TDS works both ways.  The Trumpanzees have it also but in a different form from the anti trump groups. 

Yep - that is the basic idea...See a god can NEVER lie so...

Only if you're a Trump loyalist.