a form of encephalitis, or sleeping sickness, epidemic in the period from 1915 to 1926
See encephalitis lethargica in American Heritage Dictionary 4
(lə-thärˈjĭ-kə)
noun
A viral epidemic encephalitis marked by apathy, paralysis of the extrinsic eye muscle, and extreme muscular weakness. It occurred in various parts of the world between 1915 and 1926. Also called sleeping sickness, sleepy sickness.