The correct answer is Isolated Language.
An Isolated Language is defined as a natural language that has no genealogical relationship with other languages, that is, an ancestor with another language has not been found. In addition to Basque, Korean, Sumero and Ainu are examples of isolated language. However, many linguists claim that these languages if they are related to other languages, it is simply that the languages to which they were related have not survived.
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