McCarthyism refers to the political practice of making accusations of subversion or treason without proper evidence, particularly associated with U.S. Senator Joseph McCarthy in the early 1950s. It was characterized by heightened fears of communist influence during the Cold War, leading to aggressive investigations and the blacklisting of individuals in various sectors, including government, entertainment, and education. The term has since come to symbolize the dangers of political repression and the violation of civil liberties in the name of national security.