The Language spoken in Atlantis is, obviously, unknown. However, as Atlantis was a military alliance and according to Plato, spread over hundreds of miles, it is likely that its territory included a number of different spoken languages. Nevertheless, readers might be entertained by some of the wilder speculation (a) that the subject has generated.
Edgar Cayce ‘revealed’ that the Atlanteans did not need language as they used telepathy to communicate!*John Van Auken , a director of Cayce’s A.R.E., tells us that this changed when “As we Children of God, or “Morning Stars” as the book of Job referred to us, pushed our minds deeper and deeper into matter (this third dimensional plane), we became more individualized, and our expansive consciousness was narrowed into this world of form and physicality. When we were finally ‘out of Spirit, out of the ability to have all the attributes of the spiritual or unseen forces…’ (Cayce Reading 364-10) and more fully in matter, then we moved toward writing and speaking.” There is lots more balderdash like that on the same site(c).*
In the seventeenth century, Olof Rudbeck concluded that Swedish was the language of Atlantis and the foundation for Greek and Latin. In recent times Felice Vinci claimed that Homeric Greeks spoke Finnish, while Skender Hushi thinks Albanian was the language of Atlantis.
Atlantean (Dig Adlantisag), was a language created for the film Atlantis: The Lost Empire by Marc Okrand, who worked with John Emerson, a designer at Disney, to produce an alphabet for the language.(b)
(a) http://occult-advances.org/languages.shtml (link broken Nov. 2019)