Jingoism is extreme patriotism in the form of aggressive foreign policy. In practice, it is a country’s advocation of the use of threats or actual force against other countries in order to safeguard what it perceives as its national interests. Colloquially, it refers to excessive bias in judging one’s own country as superior to others – an extreme type of nationalism.
The term originated in Britain, expressing a combative attitude towards Russia in the 1870s. During the 19th century in the United States, journalists called this attitude “spread-eagleism”. Jingoism did not enter the American vocabulary until near the turn of the 20th century. This nationalistic belligerence was intensified by the sinking of the battleship USS Maine in Havana harbour that led to the Spanish-American War of 1898.
The chorus of a song by G. H. MacDermott (singer) and G. W. Hunt (songwriter) commonly sung in British pubs and music halls around the time of the Russo-Turkish War gave birth to the term. The lyrics included the phrase: We don’t want to fight but by Jingo if we do. “By Jingo” had long been used to avoid saying “by Jesus”. Referring to the song, the specific term “jingoism” was coined as a political label by the prominent British radical George Holyoake in a letter to the Daily News on 13 March 1878.
Source: Wikipedia