Atlantis - Fictional island in Plato's works, now a synonym for supposed prehistoric lost civilizations

"Atlantis is a fictional island mentioned in an allegory on the hubris of nations in Plato's works Timaeus and Critias, where it represents the antagonist naval power that besieges "Ancient Athens", the pseudo-historic embodiment of Plato's ideal state in The Republic. In the story, Athens repels the Atlantean attack unlike any other nation of the known world, supposedly bearing witness to the superiority of Plato's concept of a state. The story concludes with Atlantis falling out of favor with the deities and submerging into the Atlantic Ocean. - Wikipedia"