In the communist lexicon, anti-revisionism is opposition to attempts to revise, modify, or abandon the fundamentals of revolutionary theory and practice. In this view, reformism within communism is rejected as representing dangerous concessions to communism's adversaries.
Because different political trends trace the historical roots of revisionism to different eras and leaders, there is significant disagreement today as to what constitutes anti-revisionism. Therefore, modern groups which describe themselves as anti-revisionist fall into several categories. They universally tend to oppose Trotskyism and de-Stalinization; however, some uphold the works of Marx, Engels, Lenin, Stalin, and Mao (Maoism or Marxism–Leninism–Maoism), and some the works of Marx, Engels, Lenin and Stalin while rejecting Mao (Marxism–Leninism). In addition, other groups uphold various less well-known historical leaders, such as Enver Hoxha (Hoxhaism).
Historically, anti-revisionists presented a critique of the official Communist Parties "from the left" for having abandoned orthodox Marxism–Leninism (becoming "revisionist" and insufficiently revolutionary). The terminological disagreement can be confusing because different versions of a left-right political spectrum are used. Anti-revisionists consider themselves the ultimate leftists on a spectrum from communism on the left to imperialist capitalism on the right. But Stalinism is often labeled rightist within the communist spectrum and left communism leftist. In the wake of Khrushchev's speech to the 20th Congress of the C.P.S.U, the defense of Stalin and his legacy became a hallmark of anti-revisionism. In the 1970s the anti-revisionist movement expanded and diversified to encompass those communists who rejected a pro-Soviet orientation for one aligned either with Chinese or Albanian positions.