Ultimately, whether blatant misrepresentation of physical facts or not, it's claiming to be merely reporting facts when in fact the underlying intention is to misrepresent the truth, or merely not care about the truth in an attempt to cause a reader's mind to believe something you want them to believe while at the same time they themselves believe they have just read an unbiased presentation of news. I.e 'What Actually Happened."
Also, it's fine to be biased so long as you're clear that you take a certain position. Breitbart doesn't pretend to not have a viewpoint. The MSM does. It's fine to be biased so long as everyone knows you are. (Many here would argue, as would I, that at the end of any year of reporting, Breitbart has in fact been less biased than the MSM.)
For CNN, NYT, practically every alphabet org, and the other many many many orgs that qualify as fake news, they are blatantly lying by not admitting they are carrying a propaganda message for certain interests. Even a story that is 100% technically factual leaves out facts, is worded a certain way, was handpicked to cause the reader/listener to walk away with a negative attitude toward the right, or a less negative attitude or positive attitude of the left.
I don't 'trust' any news organization ... I read, and read more, and wait, and after taking in enough points, the true shape appears. In most cases, I find that conservative news sources tend to be full of opinion but do not leave out significant facts (because they know their listeners/readers will skewer them - conservatives prefer the truth backed up by evidence and statistics ... i.e. proof ...) so usually I can be pretty certain that the more mainstream conservative sources will not totally misrepresent reality by either blatantly lying about it or leaving out significant portions. They know the truth will come out. The CNN's don'e have to worry about that because their audience doesn't follow up on truth ... they merely want to be told what they already want to believe, and leave it at that.
In the end, though, 99% of communication is non-verbal, and even verbal communication is 99% about what's included and what's left out.
So to me fake news is ... like the judge in the (60's?) who defined community standards said 'lewd and lascivious' can not be defined but you know it when you see it ...
We all know what fake news is. Determining the actual truth is a matter of sifting through 5 - 50 points of data and then waiting for more information to come up, and the picture appears.
Liberals don't have an interest in facts, only confirming evidence. So, they seek only 1 point of data, maybe another confirming one (CNN then the NYT) ... and then they put their heads in the sand. I have a friend whos a liberal voter -> not an activist or leader -> and she simply can not stand any fact. Any time she brings up some horrible thing Trump did or said, in a happy triumphant voice, like she's finally got me, I put the comment in context, note how it was twisted and taken out of context (or, frankly, sometimes he just says something stupid) ... and it's never long before she doesn't want to here me be rational and factual ... because the MERE pointing out of facts highlights that she's been misled by her media sources.