The word has ancient linguistic roots as a noun describing an insane person - luaticus (L), lunatik (Middle English), lunatique (Old French). Its continued use for classifying the insane persisted until the mid nineteen century when progressive psychiatric schools abetted by liberal intelligentsia , and other profound thinkers of the gentler, kinder socialist forces morphed it into a politically correct less critical manor of describing the insane, ‘psychologically disturbed’. More contemporary understandings and use are ascribed to other noun forms, that is, Obama, and federal bureaucrat.
