Answer:
1. Language isolates are in effect language families consisting of a single language. Commonly cited examples include Ainu, Basque, Sumerian, Elamite, and Vedda, though in each case a minority of linguists claim to have demonstrated a relationship with other languages.
2. A language isolate, in the absolute sense, is a natural language with no demonstrable genealogical (or "genetic") relationship with other languages, one that has not been demonstrated to descend from an ancestor common with any other language. Language isolates are in effect language families consisting of a single language.