A language isolate is a natural language with no demonstrable genetic relationship with other living languages. Examples include Basque, Ainu, Burushaski, and Japanese.
Some languages became isolates in historical times, after all their known relatives became extinct. The Pirahã language of Brazil is one such example, the last surviving member of the Mura family. Others, like Basque, have been isolates for as long as their existence has been documented.
Genetic relationship
The term "genetic relationship" is meant in the sense of historical linguistics, which claims that almost all languages spoken in the world today can be grouped by derivation from common ancestral languages into a relatively small number of families. Thus, for example, English is related to other Indo-European languages, and Mandarin to many other Sino-Tibetan languages. By this criterion, each language isolate constitutes a family on its own — which explains the exceptional interest that those languages have received from linguists.
Looking for relationship
It is possible that all languages spoken in the world today are genetically related, by descent from a single ancestral tongue; the established language families would then be only the upper branches of the genealogical tree of all languages. For this reason, isolate languages have been the object of uncountable studies seeking to uncover their genealogy. Thus, for instance, Basque has been compared with every living and extinct language family, from Sumerian to the South Caucasian — without convincing results.
Isolate, not Isolated
One should not confuse the concept of a language isolate with a language whose speakers are isolated in some sense, e.g. because they have little contact with other cultures (like the language of Easter Island), or because they live far away from the regions where related languages are spoken (like the Malagasy language of Madagascar, whose closest relatives are spoken in Southeast Asia). These two languages are definitely not isolates.
List of language isolates
Below is a list of known language isolates, along with notes on possible relations to other languages or language families:
| Language | Comments |
| Ainu | Endangered language, spoken in northern Japan. |
| Basque | No known living relatives, found in the Basque region of France and Spain. Aquitanian is commonly regarded as a direct ancestor of Basque. Some linguists have claimed similarities with various languages of the Caucasus, especially because of its ergative case system, but the resemblances seem superficial. Other linguists have proposed a relation to Iberic. |
| Birale (Ongota) | Often considered Afroasiatic |
| Burushaski | Little information available. |
| Elam | Extinct language of Elamite Empire; some conjecture a relationship to the Dravidian languages |
| Etruscan | Language of the ancient Etruscans in southern Italy, not well understood at present |
| Hadza | Often listed as an outlier among the Khoisan languages |
| Iberic | There are lexical coincidences with Basque, but it is hard to know if they are more than a result of vicinity. |
| Jalabe (Jalaa) | |
| Japanese | Possibly related to Korean language, though not yet proven. Connections to the Altaic languages have also been proposed. See Altaic hypothesis for these theories. |
| Ket | No known relatives. Some linguists have attempted to show a relationship with Burushaski. |
| Korean | Possibly related to Japanese language, though not yet proven. Connections to the Altaic languages have also been proposed. See Altaic hypothesis for these theories. |
| Kwadi | Often listed as an outlier among the Khoisan languages |
| Mekejir (Shabo) | Often considered Nilo-Saharan |
| Meroitic | Extinct language of ancient Nubian kingdom |
| Nahali | |
| Nivkh | or Gilyak. A Palaeosiberian language spoken in the lower Amur River basin and on the Sakhalin Islands; Ainu is also spoken on Sakhalin. |
| Oropom | Possibly nonexistent. |
| Sandawe | Often listed as an outlier among the Khoisan languages |
| Sumerian | Long-extinct language of ancient Sumeria. |
| Taiap | |
| Ticuna | |
| Yukaghir | Connections to Uralic Languages have been proposed |