While the verified answer is correct, if you are asking from Plato then the best answer as stated in the lesson as well is 'the deaths of young soldiers who might have become skilled professionals had they survived." They are referred as the lost generation because most of them died due to the war and never got a chance to grow up and achieve their true goals. They died before they could go to college, start a career, and have a family. Therefor the "Lost Generation."