A Language isolate is a language with no clear relationship to or affinity with other languages. Unlike English, which is clearly related to other Germanic languages, or the various Chinese languages, isolates generally stand apart from their surrounding languages in terms of their phonology, grammar, and syntax.
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. |
| Basque | No known relatives. Some linguists have attempted to show relationship with the Caucasian languages or Iberic. |
| Burushaski | Little information available. |
| Etruscan | |
| Gilyak or Nivx. A Palaeosiberian language spoken in the lower Amur basin and on Sakhalin, where their neighbours are the Ainu. | |
| Iberic | There are lexical coincidences with Basque, but it is hard to know if they are more than a result of vicinity. |
| Ket | No known relatives. Some linguists have attempted to show relationship with Burushaski. |
| Japanese | Very likely related to Korean language, though not yet proven. Connections to the Altaic languages have also been proposed. |
| Korean | Very likely related to Japanese language, though not yet proven. Connections to the Altaic languages have also been proposed. |