Fake news, according to Cambridge Dictionary:
false stories that appear to be news, spread on the internet or using other media, usually created to influence political views or as a joke
Believe it or not (don't before reading my source) the American Dialect Society, chose fake news as their word of the year for 2017.
Another term, also recently popularised by its use in American politics, is an alternative fact. Collins Dictionary defines it as:
- a theory posited as an alternative to another, often more widely accepted, theory
- a statement intended to contradict another more verifiable, but less palatable, statement