Chauvinism (/ˈʃoʊvɪnɪzəm/ SHOH-vih-nih-zəm) is the unreasonable belief in the superiority or dominance of one's own group or people, who are seen as strong and virtuous, while others are considered weak, unworthy, or inferior. The Encyclopaedia Britannica describes it as a form of "excessive and unreasonable" patriotism and nationalism, a fervent faith in national excellence and glory.

In American English, since the 1940s, the word has increasingly been used as a shorthand for male chauvinism, a trend reflected in Merriam-Webster's Dictionary, which, as of 2018, began its first example of use of the term chauvinism with "an attitude of superiority toward members of the opposite sex".

According to legend, French soldier Nicolas Chauvin was badly wounded in the Napoleonic Wars and received a meager pension for his injuries. After Napoleon abdicated, Chauvin maintained his fanatical Bonapartist belief in the messianic mission of Imperial France, despite the unpopularity of this view under the Bourbon Restoration. His single-minded devotion to his cause, despite neglect by his faction and harassment by its enemies, started the use of the term. The French term had originated in the early 1830s based on the character of Nicolas Chauvin in the play The Tricolour Cockade by the Cogniard Brothers, and was later adopted into English, being recorded in American English in 1867.

Chauvinism has extended from its original use to include fanatical devotion and undue partiality to any group or cause to which one belongs, especially when such partisanship includes prejudice against or hostility toward outsiders or rival groups and persists even in the face of overwhelming opposition. This French quality finds its parallel in the English-language term jingoism, which has retained the meaning of chauvinism strictly in its original sense; that is, an attitude of belligerent nationalism.

In 1945, political theorist Hannah Arendt described the concept thus:

Chauvinism is an almost natural product of the national concept in so far as it springs directly from the old idea of the "national mission". ... [A] nation's mission might be interpreted precisely as bringing its light to other, less fortunate peoples that, for whatever reason, have miraculously been left by history without a national mission. As long as this concept did not develop into the ideology of chauvinism and remained in the rather vague realm of national or even nationalistic pride, it frequently resulted in a high sense of responsibility for the welfare of backward people.

In this sense, chauvinism is irrational, in that no one can claim their nation or ethnic group to be inherently superior to another.

A historical example of chauvinism from the century following Chauvin was the German-Jewish poet Ernst Lissauer, whose extreme nationalism after the outbreak of World War 1 included writing the "Hymn of Hate against England" ("Haßgesang gegen England") in 1915. As David Aberbach remarks, "There is nothing in modern Hebrew literature, however devoted to the cause of Jewish sovereignty, remotely comparable to the super-chauvinistic Hassgesang ('Hate Song for England')..."