From Longman Dictionary of Contemporary EnglishMcCarthyismMc‧Car‧thy‧is‧m /məˈkɑːθi-ɪzəm $ -ɑːr-/ noun [uncountable] (in the US in the 1950s) the searching for and removal from public employment of all those believed to be Communists, which was carried out under Senator Joseph McCarthy. Many of the people accused were blacklisted (=not allowed to work) or imprisoned. People were encouraged to give the names of their friends and people they worked with to protect themselves. Today most Americans are embarrassed about this period in their history, and people who refused to give information about themselves or others are admired. McCarthyism is sometimes used to mean any accusation of disloyalty to your country that is made without proof. → see also blacklist1, communist1, HUAC, the
