Misinformation is information that is not true. In careful use it is simply wrong information — a false number, a mixed-up fact, a story that did not happen — whether the speaker knew or not. Learner dictionaries often add “especially when someone means to deceive,” and in the news that is how people usually hear it: false claims that spread, especially online, to push a feeling or a side. Though actually, the stricter word for a planned lie-campaign is disinformation. Journalists, teachers, and officials use misinformation; it sounds serious. It is uncountable: we say “a lot of misinformation,” not usually “a misinformation.”