Populism is a highly contested political concept that champions the "common people" in opposition to a perceived elite, often carrying strong anti-establishment sentiments. The term first appeared in English in 1858, later being applied to the Russian narodniki agrarian movement of the 1860s–70s and the U.S.-based People's Party (1880s–1900s), which advocated for small farmers and progressive reforms. Its meaning shifted dramatically over time, including a French literary genre in the late 1920s—championed by Léon Lemonnier—and becoming a defining feature of post-war Latin American politics, where charismatic leaders mobilized newly urbanized populations. Academic usage broadened significantly in 1954, when sociologist Edward Shils linked it to McCarthyism in the U.S. and political scientist Hélio Jaguaribe applied it in Brazil, moving it beyond purely historical study. Despite its widespread use, populism remains vaguely defined and often contradictory, used pejoratively in some contexts but openly embraced as a positive label in others, particularly in Latin America. This evolution across continents and eras underscores how the concept has become a powerful yet ambiguous tool in global political discourse.