Ultranationalism is defined as "extreme nationalism that promotes the interest of one state or people above all others", or simply "extreme devotion to one's own nation".

Cyprian P. Blamires asserts that ultranationalism is essentially racist and is known to legitimise itself "through deeply mythicized narratives of past cultural or political periods of historical greatness or of old scores to settle against alleged enemies". It can also draw on "vulgarized forms of physical anthropology, genetics and eugenics to rationalize ideas of national superiority and destiny, of degeneracy and subhumanness".