Khoisan languages
The Khoisan languages (also Khoesan or Khoesaan) are a group of African languages originally classified together by Joseph Greenberg. Khoisan languages share click consonants and do not belong to other African language families. For much of the 20th century, they were thought to be genealogically related to each other, but this is no longer accepted. They are now held to comprise three distinct language families and two language isolates.