Fake news poses a serious threat to knowledge and democracy. In order to address this threat, it is important to understand exactly what fake news is. After surveying the various definitions that have been proposed in the philosophical literature, we argue that fake news is best understood as counterfeit news. A story is genuine news if and only if it has gone through the standard modern journalistic process involving professionally trained reporters, fact checkers, and editors. And a story is counterfeit news if and only if it is not genuine news, but is presented as genuine news, with the intention and propensity to deceive. This analysis is a contribution to ‘systems-oriented social epistemology’ (Goldman, Alvin I. 2011. “A Guide to Social Epistemology.” In Social Epistemology: Essential Readings, edited by Alvin I. Goldman, and Dennis Whitcomb, 11–37. New York: Oxford University Press). Various social institutions, such as science and journalism, provide important epistemic benefits to society. But unscrupulous agents are often motivated to leverage the epistemic authority of these institutions by counterfeiting them. People can thereby be misled and/or lose faith in these institutions. Thus, society may suffer significant epistemic costs when such counterfeits proliferate.