Revisionism is a word which has several meanings.

• Among historians, revisionism has traditionally been used in a completely neutral sense to describe the work or ideas of a historian who has revised a previously accepted view of a particular topic. As historical research techniques change many fields of research go through periods of controversy as younger historians seek to revise established knowledges.
  • This usage has declined amongst some historians because within the field of Holocaust studies revisionism has come to specifically designate historical or pseudo-historical work which aims to deny the extent of the Jewish Holocaust.
  • More generally, revisionism is used by non-historians as a pejorative term for biased historical work which denies that some past events took place. See historical revisionism.

• Territorial revisionism is sometimes used as an euphemism for revanchism. The term has some usage in European post-Cold War debate, where many ethnic minorities hope to change the state borders drawn up after World War II.

• In the history of socialism, the word revisionist was used in the late 19th century to describe writers such as Eduard Bernstein and Karl Kautsky who sought to revise the teachings of Karl Marx by claiming that a violent revolution was not necessary to achieve socialism. See reformism.

• In the 1940s and 1950s within the international Communist movement, revisionism was used to describe Communists who focused on consumer goods production instead of heavy industry, accepted national differences and encouraged democratic reforms. Revisionism was one of the charges leveled at national communists or Titoists in a series of purges beginning in 1949 in Eastern Europe. After Stalin's death revisionism became briefly acceptable in Hungary during Imre Nagy's government (1953-1955) and in Poland during Wladyslaw Gomulka's government, although neither Nagy nor Gomulka described themselves as revisionists.

• Following the Soviet repression of the Hungarian Revolution in 1956, many people, particularly intellectuals, resigned from western Communist parties in protest. They were sometimes accused of revisionism by "loyalist" Communists. E. P. Thompson's New Reasoner was an example of this revisionism. This movement eventually became known as the New Left.

• In the early 1960s, Mao Zedong and the Communist Party of China revived the term revisionism to attack Nikita Khrushchev and the Soviet Union over various ideological and political issues, as part of the Sino-Soviet split. The Chinese routinely described the Soviets as "modern revisionists" through the 1960s. This usage was copied by the various Maoist groups that split off from Communist parties around the world.

• Revisionist Zionism was a movement founded by Vladimir Jabotinsky, who argued that the terms of the British Mandate in Palestine should be revised to make explicit the objective of creating a Jewish state there. Today's Likud party is a direct descendant of the Revisionists.