An anachronism (from the Greek ἀνά ana, 'against' and χρόνος khronos, 'time') is a chronological inconsistency in some arrangement, especially a juxtaposition of people, events, objects, language terms and customs from different time 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 example of that would be films including dinosaurs and prehistoric human beings living side by side, but they were, in reality, millions of years apart.)
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 intentionally for purposes of rhetoric, propaganda, comedy, or shock. Unintentional anachronisms may occur when a writer, artist, or performer is unaware of differences in technology, terminology and language, customs and attitudes, or even fashions between different historical periods and eras.
Examples include: condemnation of Columbus as a genocidal imperialist; revisionist approaches to Hiroshima and slave labour; anti-Communist positions of literary personalities