An anachronism (from the Greek ἀνά ana, "against" and χρόνος khronos, "time") is a chronological inconsistency in some arrangement, especially a juxtaposition of persons, events, objects, or customs from different periods. The most common type of anachronism is an object misplaced in time, but it may be a verbal expression, a technology, a philosophical idea, a musical style, a material, a plant or animal, a custom, or anything else associated with a particular period that is placed outside its proper temporal domain.
An anachronism may be either intentional or unintentional. Intentional anachronisms may be introduced into a literary or artistic work to help a contemporary audience engage more readily with a historical period. Anachronism can also be used for purposes of rhetoric, comedy, or shock. Unintentional anachronisms may occur when a writer, artist, or performer is unaware of differences in technology, language, customs, attitudes, or fashions between different historical eras.
Examples include: condemnation of Columbus as a genocidal imperialist; revisionist approaches to Hiroshima and slave labour; anti-Communist positions of literary personalities