It turns out there is no generally agreed upon definition of fake news. Some define it very narrowly:
“Newspaper articles, television news shows, or other information disseminated through broadcast or social media that are intentionally based on falsehoods or that intentionally use misleading framing to offer a distorted narrative”. Kavanagh, Jennifer, and Rich, Michael D. Truth Decay : An Initial Exploration of the Diminishing Role of Facts and Analysis in American Public Life. Santa Monica, California: RAND, 2018.
Others include various types of mis- and disinformation under the umbrella of fake news. Clare Wardle in "Fake news. It's complicated." provides a helpful typology of 7 different types of misinformation, along with a graphic of the motivations behind each type.