Spurious languages are languages that have been reported as existing in reputable works, when subsequent research has demonstrated that the language in question did not exist. Some spurious languages have been proven to not exist. Others have very little evidence supporting their existence, and have been dismissed in later scholarship.
Some alleged languages turn out to be hoaxes, such as the Kukurá language of Brazil or the Taensa language of Louisiana. Others are honest errors that persist in the literature despite being corrected by the original authors; an example of this is Hongote, the name given in 1892 to two Colonial word lists, one of Tlingit and one of a Salishan language, that were mistakenly listed as Patagonian. The error was corrected three times that year, but nonetheless "Hongote" was still listed as a Patagonian language a century later in Greenberg (1987).