A language is called unclassified ,
- if their assignment to a language family has not yet succeeded or is likely to be impossible,
- however, it cannot be regarded as isolated (i.e., according to the current state of knowledge, it cannot be proven to be related to any other language).
There are several possible reasons for a language to be "unclassified":
- the language has died out and has been passed down so weakly that a classification with the available material is not possible. (A classification would only be possible if new material became known about this language.)
- the language is (still) spoken, but has not yet been sufficiently researched to be able to assign it to a language family or to say with great certainty that it is isolated. (The prerequisite for a classification is therefore more detailed research into this language.)
- a language, even with good research, can be “unclassified” if it exhibits characteristics of two different language families. Such languages are also referred to as “hybrid” or “ mixed languages ”. Also Pidgin and Creole languages are not classifiable as they include components from different language families.
In practice, the boundaries between “isolated” and “unclassified” are not very sharp.