This subject can quickly become a fascinating epistemological journey into solipsism, semiotics, and cognitive biases.
A "lie" implies intent to deceive or mislead, but not all false facts are shared with such intent. You may be interested in Harry Frankfurt's 1986 essay On Bullshit [0] and the 2005 book of the same name, which has been discussed on HN before [1].
[0] On Bullshit: http://www2.csudh.edu/ccauthen/576f12/frankfurt__harry_-_on_...
[1] https://press.princeton.edu/books/hardcover/9780691122946/on...